Avanafil (Stendra) and sildenafil (Viagra) are both PDE5 inhibitors, and their labels differ mainly in timing guidance, tablet strengths, and some dose rules. No evidence reviewed here shows that one works better for everyone. Head-to-head studies are few, one was company-funded, and indirect analyses point in other directions, so your clinician’s judgment about your health and medicines matters most.
If you’re comparing avanafil vs sildenafil, you’ve probably seen two claims: that avanafil starts working sooner, and that sildenafil has a longer track record. Both ideas have some basis, and both need context. Avanafil and sildenafil are PDE5 inhibitors (phosphodiesterase type 5 inhibitors), prescription tablets that help blood flow into the penis when you’re sexually aroused. They share the same basic mechanism and many of the same safety rules, but the details in their official labeling are not identical.
This article lines up what the Stendra and Viagra labels say about timing, food, tablet strengths, side effects, and warnings. It also looks at the small number of head-to-head studies and the indirect comparisons, and it says plainly where the evidence runs out. We make no claim that either medicine is better or best, because the studies can’t support one, and because the right choice depends on your health history, your other medicines, and what you and your prescriber decide together.
Think of this as one comparison in a larger set. For the broader sildenafil and tadalafil picture, see sildenafil vs tadalafil. If you’re also wondering how a brand tablet compares with its generic version, Viagra vs generic sildenafil and Cialis vs generic tadalafil cover that question. For the other pairings, read vardenafil vs sildenafil, avanafil vs tadalafil, and the three-way sildenafil vs vardenafil vs tadalafil comparison.
Nothing here replaces your prescriber’s or pharmacist’s advice, and it isn’t a recommendation to start, stop, or change any medicine.
- Both are PDE5 inhibitors with the same core safety rules: never with nitrates or riociguat, and urgent care for an erection lasting more than 4 hours or sudden vision or hearing loss.
- The labels differ on timing (avanafil about 15 minutes before activity, sildenafil about 1 hour with a 30-minute to 4-hour window), tablet strengths, and some dose limits.
- Head-to-head evidence is limited: one 220-man randomized trial and one 160-man post-prostatectomy study, with different results.
- Cross-label side effect tables use different trials, so they can’t be ranked against each other.
- A prescriber who knows your health history and medicine list should guide the choice.
What Avanafil and Sildenafil Have in Common
Before the differences make sense, it helps to see how much these two medicines share. Both are prescription tablets for erectile dysfunction (ED), meaning trouble getting or keeping an erection firm enough for sex. Both follow the same general mechanism, and both labels carry similar big-picture safety rules. Starting from the overlap keeps the differences in proportion.
Two PDE5 inhibitors with one basic job
Avanafil and sildenafil belong to the same medicine class, so the first question is what that class does and what it asks of you. The next two sections cover the mechanism and the conditions both labels attach to using it.
How both medicines work
An erection starts with signals that relax smooth muscle in the penis so blood can flow in. PDE5 is an enzyme that breaks down one of the chemical messengers in that process. PDE5 inhibitors block that enzyme, which lets the relaxing signal last longer when arousal is already happening. The NIDDK treatment page describes PDE5 inhibitors as oral medicines that improve blood flow to the penis and may help you get and keep an erection.
The key phrase is “when arousal is already happening.” The Stendra label states that sexual stimulation is required for a response, and the same logic applies to sildenafil. Neither tablet creates desire or produces an erection on its own. If your main concern is low desire rather than firmness, that is a separate topic, covered in our low libido guide. For the full background on sildenafil itself, see sildenafil for ED.
What both require before you start
Both medicines are prescription-only, and both labels expect a clinician to weigh your heart health, blood pressure, and other medicines first. Sexual activity itself puts demands on the heart, and the Viagra label says there is potential cardiac risk of sexual activity in people with existing cardiovascular disease. The Stendra label goes further and lists situations where it isn’t recommended, such as a heart attack, stroke, or life-threatening arrhythmia within the past 6 months, or resting blood pressure below 90/50 or above 170/100 mmHg.
Both labels also share the same two hard stops: nitrates and guanylate cyclase stimulators such as riociguat. That is explained in detail later. For now, the practical point is that you can’t judge fit from a comparison article. A prescriber needs your full history, and you should tell them and your pharmacist about every medicine and supplement you use, including over-the-counter products and herbal items.
Brands, labels, and generics
Names matter here because people use “Viagra” and “sildenafil,” or “Stendra” and “avanafil,” interchangeably. The next two sections sort out which products exist and how this article reads the evidence.
Stendra, Viagra, and tablets from other labelers
Stendra is the brand name for avanafil, and Viagra is the brand name for sildenafil. DailyMed, the National Library of Medicine’s label database, lists a Stendra label from Metuchen Pharmaceuticals and a Viagra label from Viatris Specialty, revised in November 2023. It also lists an avanafil tablet label from Camber Pharmaceuticals, revised in November 2025, filed under the abbreviated new drug application pathway that generics use.
Same active ingredient does not mean you should compare by name alone. Sildenafil tablets from many labelers exist, and our brand-versus-generic sildenafil article explains how FDA treats them. This article compares the two active ingredients as the brand labels describe them. If you hold a prescription for a specific product, the label that came with it is the one to read.
How this comparison was built
The facts below come from the current labeling on DailyMed (the Stendra label updated July 18, 2024 and the Viagra label updated November 17, 2023), from the published head-to-head studies we could open, and from two network meta-analyses (statistical comparisons that combine many trials). We checked each number against the page it came from, and where we couldn’t, we say so. Research for this article was completed on October 12, 2026.
Labeling is not the same as head-to-head evidence. Each label summarizes that company’s own trials against placebo, run at different times in different groups of men. That’s useful for safety rules and dosing, but it can’t tell you which drug performs better. The few direct comparisons are covered in their own section, and we flag their limits right alongside the results.
Timing: Onset, Peak Levels, and Half-Life
Timing is where avanafil and sildenafil look most different on paper. The labels set different advice about when to take a tablet, and the blood-level data show different peak times. Still, “when it peaks” and “how soon it helps” are not the same thing, and neither equals “how long it lasts.” This section separates those ideas.
What the labels say about timing
Labels give two kinds of timing information: instructions written for the person taking the tablet, and measurements from small studies of how the drug moves through the body. They are related, but they answer different questions.
Dosing windows before sexual activity
The Stendra label gives a recommended starting dose of 100 mg, taken as needed as early as approximately 15 minutes before sexual activity, up to once per day. The label’s dose steps are timed the same way: 200 mg about 15 minutes before activity, or 50 mg about 30 minutes before. The Viagra label recommends 50 mg as needed about 1 hour before sexual activity, with a window from 30 minutes to 4 hours, also up to once per day.
Notice that these are instructions, not a promise about the clock. “As early as approximately 15 minutes” is dosing guidance, not a guarantee that every tablet works by then. Your prescriber sets the dose for you, and the label’s numbers describe a starting point and allowed adjustments, not something to change on your own. For sildenafil specifically, how long Viagra takes to work goes deeper.
| Feature | Avanafil (Stendra) | Sildenafil (Viagra) |
|---|---|---|
| Tablet strengths | 50 mg, 100 mg, 200 mg | 25 mg, 50 mg, 100 mg |
| Label’s recommended starting dose | 100 mg | 50 mg (for most patients) |
| Timing before sexual activity | As early as about 15 minutes (100 mg or 200 mg); about 30 minutes (50 mg) | About 1 hour; window 30 minutes to 4 hours |
| Maximum frequency | Once per day | Once per day |
| Food | May be taken with or without food | May be taken with or without food |
Source note: Stendra label (DailyMed, updated July 18, 2024) and Viagra label (DailyMed, revised November 2023); label text summarized, not a dosing recommendation. A prescriber sets the dose for the individual; this table only restates what the labels say.
Peak levels and half-life
Peak time (Tmax) is how long it takes blood levels to reach their highest point after a tablet is swallowed. In the fasted state, the Stendra label reports a median Tmax of 30 to 45 minutes. The Viagra label reports peak concentrations within 30 to 120 minutes, with a median of 60 minutes. Terminal half-life, the time it takes the blood level to fall by half, is about 5 hours for avanafil and about 4 hours for sildenafil and its main breakdown product, according to the same two labels.
These figures come from pharmacology studies, which are often small and run in healthy volunteers, and they describe averages. Half-life is not the same as how long the medicine helps. A drug can be measurable in blood without producing a useful effect, and the labels don’t state a “duration of effect” in hours. If your question is about the active window for sildenafil, how long Viagra lasts takes that on directly. The peak-time gap of roughly 15 to 30 minutes between median values is real on paper, but it doesn’t translate into a promise for any one person.
What studies say about speed
Because peak time and onset are different things, researchers measure speed by asking how often an attempt leads to a successful erection within a set number of minutes. Two sources report this, and they have very different strengths.
The Stendra time-to-onset study
Section 14 of the Stendra label describes a placebo-controlled study that measured the percentage of attempts with an erection sufficient for penetration at about 15 minutes, followed by successful intercourse, over 8 weeks. The mean was 14.9% of attempts for placebo, 25.9% for 100 mg, and 29.1% for 200 mg. The medians were 0.0%, 11.1%, and 13.3%. Both avanafil doses differed from placebo (p = 0.001 and p < 0.001).
Those results help in two ways. They show avanafil produced more successful attempts at about 15 minutes than placebo did. But they also show that most attempts at that early mark were not successful, even at 200 mg, and that a typical (median) attempt did not meet the endpoint at all in the placebo group. Fifteen minutes is the earliest point the label discusses, not a point at which everyone can expect results. This study compared each dose with placebo, not with sildenafil.
The head-to-head onset finding and its limits
The only randomized trial we found that compared the two directly reported an onset measure. In a 12-week trial in India, published in the International Journal of Urology in 2022, 220 men were randomized to avanafil 100 mg or sildenafil 50 mg, each allowed to rise to a higher dose. An erection within 15 minutes (a modified Sexual Encounter Profile question) was reported for 84.8% of avanafil doses versus 28.2% of sildenafil doses (P < 0.001).
That is a large gap, and it deserves honest handling. The trial was funded by a manufacturer, Zydus Healthcare, and two authors were company employees. Men averaged about 36 to 37 years old, so the results may not describe older men or those with heart disease or diabetes. Sildenafil’s label itself advises dosing about an hour ahead, which may matter if tablets were assessed at 15 minutes. One trial, in one setting, is a signal worth noting, not a settled answer. See how long Viagra takes to work for sildenafil’s own timing evidence.
Food, Tablet Strengths, and Dose Adjustments
Practical details like meals, tablet sizes, and adjustments for age or kidney and liver health often shape day-to-day use more than the headline comparisons do. Here the two labels agree on some points and differ on others, and the differences are easy to misread if you only skim a summary.
Meals and absorption
Both labels allow their tablet with or without food, so neither one requires an empty stomach. Both also report that a high-fat meal slows how fast the drug is absorbed. What differs is the size of the reported effect.
What each label says about food
The Stendra label says avanafil may be taken with or without food, and the Viagra label says the same of sildenafil. Each also describes a high-fat meal study. For avanafil (200 mg), the Stendra label reports that the rate of absorption is reduced, with peak time delayed by a mean of 1.12 to 1.25 hours, peak concentration about 39% lower, and total exposure (AUC) down only about 3.8%. For sildenafil, the Viagra label reports a mean delay in peak time of 60 minutes, and the older 2017 label text reports a mean 29% lower peak.
In plain language, a heavy, greasy meal can make either tablet start more slowly and peak lower, while the overall amount absorbed changes much less for avanafil, per its label. Neither label sets a waiting time after eating or defines “high-fat” in grams. For the sildenafil side in detail, see sildenafil and food. If a meal seems tied to a weak response, that is a useful detail to share with your prescriber rather than something to fix by adjusting doses yourself.
What the food numbers do not tell you
It’s tempting to compare 39% with 29% and decide which drug is “more affected” by food. That comparison isn’t safe to make. Each label reports its own study, with its own volunteers, dose, and meal. We confirmed the dose only for avanafil (200 mg), and a percentage from a single-dose study of healthy volunteers doesn’t predict what happens in your body, with your stomach contents, on a particular night.
The food data also describe blood levels, not erection quality. Neither label ties the food effect to a drop in success rates, and neither gives a rule such as “wait two hours after dinner.” What the numbers do support is modest: a big meal may delay the start. If you’ve noticed a pattern, such as better results on lighter-meal days, note it with dates and amounts. That kind of record gives a clinician something concrete to work with, and it is more useful than a guess about which drug handles food better.
Daniel, 47, has taken sildenafil for several months. A friend tells him avanafil “doesn’t care about food,” and he wonders whether to ask for a switch. Before his next appointment, he writes down what he actually notices: the nights he took the tablet after a large restaurant dinner, the nights he took it on a lighter stomach, and how long he waited each time. He also lists his other medicines and one supplement. At the visit, he doesn’t ask for a particular drug. He asks his prescriber whether meals could explain the variation and whether anything on his list changes the picture. The prescriber can then weigh both labels with his history in view, and decide with him whether any change makes sense.
Hypothetical scenario for illustration only. It does not describe a real person and is not individualized medical advice.
Tablet strengths and dose steps
Dose forms look similar at first glance: both come as tablets in three strengths, and both labels cap use at once per day. The details differ in how the labels step the dose up or down and how they treat certain groups of people.
Tablet strengths and starting doses
Stendra comes in 50 mg, 100 mg, and 200 mg tablets, and the label’s recommended starting dose is 100 mg. Viagra comes in 25 mg, 50 mg, and 100 mg tablets, and the label’s recommended dose for most patients is 50 mg. The labels then let the prescriber move up or down: avanafil to 200 mg or down to 50 mg, sildenafil to a maximum of 100 mg or down to 25 mg, based on effectiveness and tolerability.
Milligrams are not interchangeable between drugs. A 100 mg avanafil tablet isn’t “twice” a 50 mg sildenafil tablet in any meaningful sense, because the two molecules differ in potency and in how the body handles them. The head-to-head trials chose their own starting pairs and dose-escalation rules, which is one reason their results can’t be turned into an equivalence chart. The American Urological Association (AUA) ED guideline says the dose should be titrated to provide optimal efficacy. For label detail on sildenafil, see Viagra dosage explained.
Age, kidney, and liver adjustments
This is one of the clearer label differences. The Viagra label says to consider a 25 mg starting dose in men over 65, in people with hepatic impairment (for example, cirrhosis), and in people with severe renal impairment (creatinine clearance below 30 mL/minute). The Stendra label says no dose adjustment is warranted based on age alone, although some older patients may be more sensitive, and no adjustment is needed for mild to moderate kidney or liver impairment.
For severe disease, though, the Stendra label goes further: it says not to use the drug in severe kidney disease (including dialysis) or severe liver disease. So the same health condition can lead to a lower starting dose on one label and a “do not use” statement on the other. That is a good reason to tell your prescriber about kidney and liver conditions, even if they seem unrelated. Only a clinician who knows your lab results can say what applies to you.
Side Effects: What Each Label Reports
Side effects are where comparison articles most often go wrong. Both labels list headache and flushing as common, which is true of the whole class. But the tables behind those lists come from different trials, so the percentages can’t simply be set side by side as a ranking.
Placebo-controlled trial data
Each label reports the reactions seen in its own placebo-controlled trials. These tables are the most reliable source for what to expect in general, as long as you read them for what they are.
Common reactions listed in each label
The Stendra label’s main table covers three placebo-controlled trials of 3 months with as-needed use. The Viagra label’s table covers fixed-dose phase II and III studies and lists reactions in at least 2% of men on treatment and more frequent than placebo. Headache and flushing top both lists. Other reactions on the Viagra list include indigestion (dyspepsia), nasal congestion, back pain, muscle pain, nausea, dizziness, and rash, along with abnormal vision, which the label describes as mostly a color tinge, with some light sensitivity or blurriness.
| Reaction | Avanafil: placebo; 50 mg; 100 mg; 200 mg | Sildenafil: placebo; 25 mg; 50 mg; 100 mg |
|---|---|---|
| Headache | 1.7; 5.1; 6.9; 10.5 | 7; 16; 21; 28 |
| Flushing | 0.0; 3.2; 4.3; 4.0 | 2; 10; 19; 18 |
| Nasal congestion | 1.1; 1.8; 2.9; 2.0 | 2; 4; 4; 9 |
| Back pain | 1.1; 3.2; 2.0; 1.1 | 2; 3; 4; 4 |
| Dyspepsia (indigestion) | Not in label’s main table | 2; 3; 9; 17 |
| Abnormal vision | Not in label’s main table | 1; 1; 2; 11 |
Source note: Stendra label (three 3-month placebo-controlled trials) and Viagra label (fixed-dose phase II/III studies), DailyMed. Each row lists placebo first, then ascending doses. Different trials, populations, and reporting rules; not a head-to-head comparison and not a ranking.
The Stendra label also reports that stopping treatment because of an adverse reaction was uncommon: 1.4% at 50 mg, 2.0% at 100 mg, and 2.0% at 200 mg, versus 1.7% on placebo.
Why the two tables cannot be lined up
It looks tempting to read the table above and conclude that avanafil causes fewer headaches. Don’t draw that conclusion from it. The two tables come from different programs run at different times. The Stendra trials averaged about 56 years of age, with about 31% of men having diabetes. The Viagra tables come from fixed-dose studies with their own reporting threshold and a placebo headache rate of 7%, compared with 1.7% in the avanafil trials, which may reflect differences in how events were collected or counted.
Doses also don’t line up. A 100 mg tablet of one drug is not equivalent to 100 mg of the other. Add differences in how side effects were asked about, and the gap between columns can’t be assigned to the medicine alone. What the tables do support is narrower: both medicines cause headache and flushing in a dose-related pattern, and a prescriber can adjust a dose if side effects are a problem. For the sildenafil side, see sildenafil side effects.
Head-to-head safety data
Only direct comparison within the same study can say something about relative tolerability. Two such studies exist, and both were small enough to leave important questions open.
Adverse events in the randomized trial
In the 220-man trial published in 2022, adverse events were reported by 9.9% of the avanafil group (11 men) and 11.0% of the sildenafil group (12 men). Most were mild, no serious or severe events occurred, and nobody stopped treatment because of one. Headache was the most common event: 8.1% (9 of 111) with avanafil and 9.2% (10 of 109) with sildenafil, a difference that was not statistically meaningful (P = 0.81).
The authors themselves note the trial was powered to detect efficacy differences, not safety differences. With only about a dozen events per group, a real difference in less common problems could easily be missed, and a 12-week window can’t speak to longer-term use. So this trial suggests the two drugs were tolerated similarly in that group, mostly younger men, but it doesn’t prove they carry identical risks. It also doesn’t change either label’s warnings.
The post-prostatectomy comparison
A second study, published in Urologia Journal, followed 160 men after robot-assisted, nerve-sparing prostatectomy at three hospitals, comparing avanafil 200 mg with sildenafil 100 mg for 6 months. Adverse events occurred in 5% of the avanafil group and 20% of the sildenafil group, and the authors concluded avanafil was better tolerated. Sexual function scores did not differ significantly overall, except that the Erection Hardness Score and one Sexual Encounter Profile question were higher in the sildenafil group.
We could read only the abstract, so group sizes, p-values, and details of randomization and blinding were not visible to us. The doses compared were the highest label doses, which could affect side effect rates. Men recovering from prostate surgery also differ from the general population of men with ED, so these findings can’t be applied to everyone. Taken with the 2022 trial, the safest summary is that the direct evidence on tolerability is mixed and limited.
Safety Rules, Interactions, and Where the Labels Differ
Most of the safety content here is shared, and it matters more than any comparison of onset or tablet size. A smaller set of rules differs by drug, mainly around enzyme-blocking medicines and certain health conditions.
Warnings both labels share
Several warnings appear in nearly identical form in both labels. They apply no matter which medicine you’re prescribed, and several are emergencies.
Nitrates and riociguat
Both labels list organic nitrates as a contraindication, meaning a situation in which the drug must not be used. Nitrates are heart and chest-pain medicines, such as nitroglycerin tablets or sprays, and combining them with a PDE5 inhibitor can cause a dangerous fall in blood pressure. Both labels also contraindicate guanylate cyclase stimulators such as riociguat, and the Stendra label names vericiguat as well. Both also list hypersensitivity (allergy) to the tablet’s ingredients.
Never take avanafil or sildenafil with nitrates in any form, or with riociguat. The combination can drop blood pressure to dangerous levels. If you take a nitrate or a heart medicine and aren’t sure of the name, ask your pharmacist before taking an ED tablet. Chest pain or fainting is an emergency: call 911. If a nitrate is ever needed urgently, tell emergency staff which ED tablet you took and when.
Hidden ingredients can create the same risk. The FDA warned in a notice dated May 29, 2026 that a supplement contained undeclared sildenafil and tadalafil, which may interact with nitrates. For the full topic, see ED medication and nitrates.
Prolonged erection, vision, and hearing
Both labels carry the same urgent-care messages. An erection lasting more than 4 hours calls for immediate medical help. The Viagra label defines priapism as painful erections lasting longer than 6 hours but still tells you to seek help at 4. Sudden loss of vision in one or both eyes is a reason to stop the medicine and get medical attention right away. So is a sudden decrease or loss of hearing. The NIDDK lists the same three problems as reasons to call a clinician right away.
The vision warning relates to NAION (nonarteritic anterior ischemic optic neuropathy), a blockage of blood flow to the optic nerve. The Stendra label cites case-crossover risk estimates of 2.15 and 2.27 and says they don’t establish causation. The older 2017 Viagra label text cites 2.15 (95% CI 1.06 to 4.34). Neither label claims that one drug is safer here. See ED medication and vision changes for more.
Where the labels differ
Most real differences show up in how each label treats interacting medicines and certain health states. They come from each drug’s metabolism and from what each company studied.
Enzyme-blocking medicines
Both drugs are processed largely by a liver enzyme called CYP3A4, so medicines that block that enzyme can raise their blood levels. Here the labels differ sharply. The Stendra label says not to use avanafil with strong CYP3A4 inhibitors such as ketoconazole, ritonavir, clarithromycin, or itraconazole. With moderate inhibitors such as erythromycin, diltiazem, fluconazole, or verapamil, it caps the dose at 50 mg, no more than once per 24 hours. With ketoconazole, avanafil exposure rose about 13-fold in the label’s study.
The Viagra label takes a dose-reduction approach instead: consider a 25 mg starting dose with strong inhibitors, and with ritonavir, do not exceed a single 25 mg dose in 48 hours. Many of these inhibitors are common antibiotics, antifungals, or HIV and heart medicines. Tell your pharmacist about every prescription, including short courses, because an antibiotic you take for a week can change what’s safe. Grapefruit is a separate topic; see sildenafil and grapefruit.
Raymond, 58, takes an alpha blocker for urinary symptoms and has a prescription for an ED tablet. His doctor then prescribes a week of clarithromycin for a chest infection. Raymond assumes a short antibiotic course doesn’t matter and plans to keep taking the tablet. Instead, he calls the pharmacy and asks whether the new antibiotic changes anything. The pharmacist checks the interaction section of the label for his tablet, sees that the antibiotic is a strong CYP3A4 inhibitor, and tells Raymond to contact his prescriber before the next dose rather than guessing. The prescriber decides what to do for the week. The takeaway is that interaction checks apply to short courses, and the person to ask is the pharmacist or prescriber, not a comparison chart.
Hypothetical scenario for illustration only. It does not describe a real person and is not individualized medical advice.
Alpha blockers, alcohol, and heart health
Alpha blockers are medicines for prostate symptoms or blood pressure that can also lower blood pressure. Both labels advise being stable on an alpha blocker before starting and starting low: 25 mg for sildenafil, 50 mg for avanafil. Both warn about additive blood-pressure lowering with antihypertensives. In healthy volunteers, the Stendra label reports that 200 mg lowered sitting blood pressure by a mean of 8.0/3.3 mmHg at the 1-hour peak, a reminder that these drugs have vascular effects. See sildenafil and blood pressure medications.
Alcohol appears differently in each label. The Stendra label warns that substantial intake (more than 3 units) can increase dizziness, headache, and orthostatic symptoms (lightheadedness on standing). The Viagra label reports that sildenafil did not potentiate alcohol’s blood-pressure-lowering effect in healthy volunteers. That doesn’t make alcohol harmless, and the studies are different in size and design. For more, see sildenafil and alcohol. Heart conditions are the other major difference: Stendra lists specific situations where it isn’t recommended, while Viagra points to potential cardiac risk of sexual activity.
What the Evidence Can and Cannot Tell You
Everything so far has described what each label says. This section steps back and asks a harder question: how much can anyone conclude from the studies that put these two drugs side by side, directly or indirectly? The honest answer is “some things, but not a verdict,” and the reasons are worth understanding.
Direct and indirect comparisons
Evidence about two drugs comes in two forms. Direct comparisons put both drugs in the same study. Indirect comparisons combine many separate trials and use statistics to estimate how drugs would stack up. They answer related questions with different strengths.
The two head-to-head studies
We found two studies that compared avanafil and sildenafil in the same group of men. The first is the 2022 randomized trial of 220 men, described earlier. Its main efficacy measure was the change in the erectile function domain of a questionnaire called the IIEF-EF (a score from a standard survey about erections). The difference in average improvement between groups was 1.1 points at week 4, 1.4 at week 8, and 2.1 at week 12, in avanafil’s favor. The authors judged week 4 non-inferior and weeks 8 and 12 superior, though the trial was designed to test non-inferiority.
The second study is the 160-man post-prostatectomy comparison, where most sexual function scores did not differ and two measures favored sildenafil. These two studies point in different directions, and they involved very different men and doses. Neither is large, and neither tested whether outcomes differ for older men, men with diabetes, or men with heart disease. A table can keep their features straight.
| Source | Who and how | Main finding | Main limits |
|---|---|---|---|
| Randomized trial, India (2022) | 220 men with ED, mean age about 36 to 37; avanafil 100 mg vs sildenafil 50 mg, each adjustable; 12 weeks | IIEF-EF gain 1.1, 1.4, and 2.1 points larger with avanafil at weeks 4, 8, 12; faster reported onset; similar side effects | Manufacturer-funded; subjective measures; small; younger men; not powered for safety |
| Prostatectomy study (2019-2020) | 160 men after nerve-sparing prostatectomy; avanafil 200 mg vs sildenafil 100 mg; 6 months | Most scores did not differ; two measures higher with sildenafil; fewer adverse events with avanafil (5% vs 20%) | Abstract only; design details not visible; specific surgical population |
| Network meta-analysis (2015) | 82 trials for efficacy; several PDE5 inhibitors including avanafil 100 mg | Authors favored sildenafil 50 mg for efficacy priority and tadalafil 10 mg for tolerability | Indirect; abstract only; older data |
| Network meta-analysis (2020) | 179 trials, 50,620 men; seven PDE5 inhibitors | Avanafil ranked among less effective for IIEF; authors favored low-dose sildenafil and tadalafil | Indirect; abstract only; conflicts with the direct trial |
Source note: Kumar et al., Int J Urol 2022; Della Camera et al., Urologia Journal 2019-2020 (abstract only); Chen et al., Eur Urol 2015; Madeira et al., World J Urol 2020 (abstracts as summarized on UroToday). Findings for the network meta-analyses come from abstracts only; we did not review their full methods.
Network meta-analyses and why they disagree
A network meta-analysis combines many trials, including drugs that were never tested against each other, by linking them through shared comparisons such as placebo. The method is useful, but it assumes the trials are similar enough to compare. When the men, doses, and outcome measures differ, the estimates can shift. We read the abstracts of two such analyses. The 2015 Chen and colleagues analysis included avanafil 100 mg among five drugs and weighed efficacy against side effects.
The 2020 Madeira and colleagues analysis pooled 179 trials and ranked avanafil among the less effective options for questionnaire scores, with its authors saying its use was hard to justify. That conclusion sits uneasily beside the 2022 randomized trial. Neither finding settles the question. We could not verify how many avanafil trials fed each model, and the reasons for the conflict, such as dose levels and trial quality, aren’t visible from abstracts.
Limits that apply to any comparison
Even a perfect pair of studies would leave limits. Some come from how ED works, and some from how comparisons are made. Understanding them can keep you from over-reading any single claim.
Why no better or best answer follows
Three reasons stand out. First, the evidence disagrees: one direct trial leans toward avanafil on questionnaire scores and onset, one direct study found mostly no difference, and one large indirect analysis ranked avanafil among the less effective options. Second, the groups differ. A trial of men in their mid-thirties tells you little about a 62-year-old with diabetes, and a surgical population is different again. Third, ED has many causes, and drug response depends on them. The sildenafil vs tadalafil pillar covers the broader choice among these medicines.
The AUA ED guideline calls shared decision-making the cornerstone of treatment, which means the choice rests on your history, preferences, other medicines, and tolerance, not on a ranking. A small average difference on a questionnaire also doesn’t say whether you would notice it. We didn’t verify a threshold for a noticeable change, so we don’t state one.
What is not established
Several questions that readers often ask have no solid answer in what we reviewed. Listing them keeps the gaps visible:
- Long-term outcomes. The direct trials lasted 12 weeks and 6 months. How the two compare over years, including continued use and satisfaction, is not established.
- Rare safety events. Neither direct study was large enough to compare uncommon outcomes such as vision or hearing events. Each label reports its own data separately.
- Older men and men with heart disease. The head-to-head participants were either mostly younger or had a specific surgical history.
- Personal preference. Whether faster measured onset matters more to a given person than familiarity, cost, or how meals fit their routine is not something these studies measured.
- Cost-effectiveness. We found no verified comparison and give no prices.
Treat each gap as a question for your prescriber, not as a hint that one drug is hiding a problem.
Common Questions About Avanafil vs Sildenafil
These are questions readers ask most often. Each answer stays close to what the labels and studies show, and each points back to the sections above for the evidence behind it. None of them is a recommendation for your situation.
Questions about speed and strength
Speed and strength are the two comparison points people raise first. The labels and studies speak to each differently, and the wording of your question changes the answer.
Is avanafil faster than sildenafil?
On paper, there is a basis for the idea. The Stendra label advises taking avanafil as early as about 15 minutes before sexual activity, while the Viagra label advises about an hour, with a 30-minute to 4-hour window. The median peak blood level is reached sooner in the avanafil label, at 30 to 45 minutes versus a median of 60 minutes. And in the 2022 trial, a much higher share of avanafil doses were rated as producing an erection within 15 minutes.
Still, “faster” is not established as a general rule. That onset finding comes from one manufacturer-funded trial, and the Stendra time-to-onset study compared avanafil only with placebo, where even 200 mg produced a successful attempt at about 15 minutes in a mean of 29.1% of attempts. Individual response varies, and a prescriber can explain how timing fits your routine. For sildenafil specifics, see how long Viagra takes to work.
Is avanafil stronger or more effective than sildenafil?
“Stronger” can mean two things. If it means the tablet number, 200 mg versus 100 mg, that is a difference in labeling units, not in power. If it means more effective, the answer is mixed. In the avanafil label’s placebo-controlled studies, SEP3 (successful intercourse) rates at the end of treatment were 27.0% on placebo versus 57.1% on 100 mg and 57.0% on 200 mg in general ED, and 20.5% versus 34.4% and 40.0% in men with diabetes. Those comparisons are against placebo, and the label’s results show avanafil beat placebo.
Against sildenafil, the direct evidence points both ways, as covered earlier. No head-to-head study reviewed here establishes that one drug is more effective for ED in general. If a medicine hasn’t helped enough, the explanation might involve dose, timing, interacting factors, or the cause of ED, and our guide to Viagra not working covers what to review with a clinician.
Questions about safety and switching
Safety and switching questions carry the most risk if answered carelessly. The short answers below stay with the label language and leave decisions to your prescriber.
Does avanafil cause fewer side effects than sildenafil?
The data are mixed. In the 2022 randomized trial, side effects were similar: 9.9% versus 11.0% of men, with headache at 8.1% versus 9.2%. In the post-prostatectomy study, adverse events were reported by 5% of avanafil users versus 20% of sildenafil users, and the authors concluded avanafil was better tolerated. The separate placebo-controlled tables in each label show lower headache percentages for avanafil, but those tables come from different trials and can’t be compared directly.
Both drugs carry the same classes of reactions, and both carry the same serious warnings. A tolerability edge in one study doesn’t mean fewer warnings apply to you. If you notice side effects on either medicine, tell your prescriber, because dose adjustments are within the label’s framework, and a clinician can check for interacting medicines. For sildenafil’s profile in depth, see sildenafil side effects.
Can I switch between them, or take both?
Don’t take both. The Stendra label says combinations with other PDE5 inhibitors or ED therapies have not been studied and are not recommended, and the Viagra label says the same of combinations with other PDE5 inhibitors or ED therapies. Two PDE5 inhibitors together could add to blood-pressure and other effects without any tested benefit. See taking Viagra and Cialis together for the same principle applied to another pair.
Switching is a prescriber decision, not a do-it-yourself step. Because the strengths, timing advice, and interaction rules differ, a switch means a new prescription with its own instructions, not a simple swap of one tablet for another at a matching number. If you’re curious about switching, bring your reasons, such as side effects, timing, or cost, and your full medicine list. Don’t stop a prescribed medicine on your own. Ask first.
Your Next Steps
A comparison article can narrow your questions, but it can’t pick a medicine for you. The most useful next step is a conversation with a prescriber who has your full history, and the most useful preparation is simple: bring specifics. This section covers what to gather, what to ask, and how to get medicine through safe channels.
Prepare for the conversation
Clinicians can work much faster with concrete details than with general impressions. A few minutes of preparation before the visit can turn “it didn’t work well” into information a prescriber can use.
What to note before the visit
Start with the basics a prescriber will ask about. Write down every medicine and supplement you use, including over-the-counter products, short antibiotic courses, and anything you take for prostate symptoms, blood pressure, or chest pain. Name any nitrate or heart medicine specifically, since that is the most important safety question for either drug. Note health conditions too, especially heart disease, diabetes, kidney or liver problems, and any past vision or hearing event.
If you’ve already tried an ED medicine, add a short record: which one, what time you took it, whether you’d eaten, whether you’d had alcohol, how long until you noticed a response, and any side effects. Dates and rough amounts are enough. You don’t need to diagnose anything, and this isn’t a self-testing exercise. The goal is a clear picture of what happened, so your clinician can look for patterns, such as timing or interacting medicines, rather than guess.
| What to note | Why it helps | What to bring up |
|---|---|---|
| All medicines and supplements | Both labels set limits for nitrates, riociguat, enzyme-blocking drugs, and alpha blockers | The full list, including short-term prescriptions |
| Timing and meals | Both labels describe food effects on absorption and give timing windows | When you took the tablet, what you ate, how long until a response |
| Side effects | Headache, flushing, and other effects are dose-related in both labels | What you noticed, how strong it was, whether it stopped you |
| Health conditions | Heart, kidney, and liver status change dose rules or whether a drug is suitable | Any diagnoses, recent cardiac events, or blood pressure readings |
| Your priorities | Preferences guide shared decision-making | Whether timing, tolerability, cost, or familiarity matters most |
Source note: Original editorial checklist based on the Stendra and Viagra labels and the AUA ED guideline (shared decision-making). A preparation aid, not a diagnostic tool.
Questions to bring to your prescriber
Questions work best when they are open rather than aimed at a particular brand. They let the prescriber use clinical judgment instead of defending a choice. The checklist below can be printed or copied into a phone note.
Getting care and avoiding risky shortcuts
Access and cost affect which medicine is practical, and risky shortcuts can undo the safety checks that make either drug appropriate. This section stays general because prices and coverage vary.
Costs, coverage, and access
We don’t give prices here because we didn’t verify any, and they vary by pharmacy, insurance plan, and whether you buy a brand or a generic. What you can describe are the cost components: the clinic or telehealth visit, any lab tests your prescriber orders, the prescription itself, and how your plan treats ED medicines. Some plans cover them partly, some exclude them, and some require prior authorization, so check your own plan’s formulary.
DailyMed lists both a brand Stendra label and an avanafil tablet label from another company, and many labelers list sildenafil, so ask whether a generic is available for what you’re prescribed. Our guide to Viagra vs generic sildenafil explains how brand and generic products relate, and how to get ED treatment covers care options and costs. Ask your pharmacist what the actual out-of-pocket cost would be before you fill a prescription, since that figure is the one that matters to you.
Counterfeit and online pills
Prescription-only medicines sold without a prescription are a safety problem, because the checks described in this article, nitrates, other medicines, heart health, are skipped. The NIDDK page on ED treatment advises against ordering an ED medicine online before talking with a health care professional. The FDA has also issued notices about products sold as supplements that contained undeclared sildenafil and tadalafil, including a May 2026 notice.
A product with a hidden drug ingredient can interact with nitrates, and you can’t see the dose on an unlabeled capsule. If you have already taken something questionable and feel unwell, seek care and bring the package. You can report problems to the FDA’s MedWatch program. If you want an ED medicine, the safest route is a licensed prescriber and a licensed pharmacy, and our ED treatment guide can help you start that conversation.
Bring your medicine list and one sentence about what you hope to change. If timing, side effects, or meals are your main concern, say so first. That helps your prescriber focus.
The labels for avanafil and sildenafil differ in real, practical ways, and the head-to-head studies are too few and too mixed to name a winner. Your health history and medicine list carry more weight than any comparison.
Avanafil and sildenafil are close relatives. They work in the same way, they share the same hard safety stops, and they require the same basic habit from you: telling every clinician and pharmacist about everything you take. Where they differ, such as dosing windows, tablet strengths, enzyme-blocking medicine rules, and adjustments for kidney or liver disease, the differences are written into their labeling, and those are worth discussing with someone who knows your history.
What the research can’t do is rank them for you. One randomized trial found modest advantages for avanafil on questionnaire scores and early onset, a post-prostatectomy study found mostly no difference, and a large indirect analysis ranked avanafil lower. Those pieces don’t fit into a neat winner, and we haven’t tried to force them to.
If you’re weighing the two, you’re in the driver’s seat for the conversation: arrive with your medicine list, your timing and meal notes, and your own priorities. For more comparisons, see vardenafil vs sildenafil, avanafil vs tadalafil, and the three-way comparison. And if you ever have an erection lasting more than 4 hours, or sudden vision or hearing loss, don’t wait for an appointment. Get emergency care.
Sources and further reading
- Stendra (avanafil) prescribing information: DailyMed , FDA label, updated July 18, 2024
- Viagra (sildenafil citrate) prescribing information: DailyMed , FDA label, revised November 2023
- Viagra label, 12/2017 text: Pfizer , older label text used for the 29% peak reduction and NAION estimate
- Avanafil tablets prescribing information: DailyMed , label from another labeler, revised November 2025
- Efficacy and safety of avanafil as compared with sildenafil: International Journal of Urology (PMC) , randomized trial, 2022
- Avanafil 200 mg versus sildenafil 100 mg after prostatectomy: Urologia Journal , prospective multicentre study, abstract
- PDE5 inhibitors trade-off network meta-analysis: European Urology (PubMed) , 2015 abstract
- Oral PDE5 inhibitors network meta-analysis: World Journal of Urology via UroToday , 2020 abstract
- Erectile Dysfunction: AUA Guideline: American Urological Association , 2018 guideline
- Treatment for erectile dysfunction: NIDDK , patient information
- X10 Natural Enhancement Supplement notice: U.S. Food and Drug Administration , notice dated May 29, 2026
Source links were checked on October 12, 2026. Guidance, drug labeling, prices, and availability can change, so confirm current details with an official source or your clinician.
