Does Stendra really work in 15 minutes?

Its label says it can be taken that soon, which is not quite the same claim but is the strongest one any US PDE5 label makes. Section 2.1, verbatim: "The recommended starting dose is 100 mg. STENDRA should be taken orally as needed as early as approximately 15 minutes before sexual activity." The 15-minute figure applies to 100 mg and 200 mg; the same section sends the 50 mg dose back to "approximately 30 minutes before sexual activity". The pharmacokinetics behind it are in section 12.3: "STENDRA is rapidly absorbed after oral administration, with a median Tmax of 30 to 45 minutes in the fasted state." VIAGRA's instruction is "approximately 1 hour before", with 30 minutes to 4 hours permitted.

Is 100 mg of Stendra the same as 100 mg of Viagra?

No, and nothing published says what it is instead. No FDA label for any of the four PDE5 inhibitors states a dose equivalence with any other, and no published trial establishes one. Twenty milligrams of tadalafil is not "equal to" 100 mg of sildenafil in any labelled or trial sense. The only dose a label will give you for a drug is that drug's own. The coincidence of the number makes this pair especially misleading: avanafil's labelled ladder is 50, 100 and 200 mg and sildenafil's is 25, 50 and 100 mg, so 100 mg is the starting dose of one and the maximum of the other. Reading the ladders across would put avanafil at half sildenafil's potency per milligram, which no source claims and which is the reason avanafil appears in no circulating equivalence table. If you are switching, you start at the new drug's own labelled starting dose.

Why does Viagra make things look blue and Stendra does not?

Because of one enzyme, and both labels say so in the same place. PDE6 sits in the retina and is involved in phototransduction; sildenafil is only 10-fold more selective for its target PDE5 than for PDE6, while avanafil is greater than 100-fold. The consequence is in each label's adverse-reaction table. VIAGRA's Table 1 reports abnormal vision in 1% at 25 mg, 2% at 50 mg, 11% at 100 mg, against 1% on placebo, footnoted as "Mild to moderate in severity and transient, predominantly color tinge to vision, but also increased sensitivity to light, or blurred vision." STENDRA's ≥2% table contains no visual reaction at any dose, and its section 6.1 records that "Across all trials with any STENDRA dose, 1 subject reported a change in color vision." Two different trial programmes, so the percentages are not a head-to-head — but the mechanism and the incidence agree, which is unusual and worth something.

How long after taking one can a nitrate be given?

Twelve hours for avanafil, and sildenafil's label declines to say. STENDRA section 4.1: "In a patient who has taken STENDRA, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered." VIAGRA section 4.1: "After patients have taken VIAGRA, it is unknown when nitrates, if necessary, can be safely administered." Neither sentence makes any combination safe — both drugs are absolutely contraindicated with organic nitrates in any form, including amyl and butyl nitrite "poppers" — but if you carry a card or tell a paramedic what you have taken, one of these drugs gives them a number to work with and the other does not.

Why is Stendra so much more expensive?

Patent status, not pharmacology. Sildenafil went generic and avanafil has not. In the CMS NADAC file dated 2026-09-16, a 200 mg avanafil tablet costs a retail pharmacy $49.48 on invoice and a 100 mg generic sildenafil tablet costs $0.12762 — a factor of 388× at each label's own maximum dose, or $395.87 against $1.02 for eight doses a month. For scale, even branded VIAGRA at 100 mg, at 655× its own generic, still costs a pharmacy less per tablet than avanafil does. None of these is a price a patient pays; NADAC records invoice cost before any dispensing fee, markup or rebate.

What does a 100 mg Stendra tablet cost?

This page cannot tell you, and the reason is worth knowing. The 16 September 2026 NADAC file prices exactly one avanafil presentation — the 200 mg tablet — and there is no 100 mg row in it, even though 100 mg is the label's recommended starting dose. The obvious workaround is not available either: no PDE5 label read for this site permits splitting a tablet, every one of them declares the FDA structured Score characteristic as 1 (a tablet of one piece, rendered by DailyMed as "no score"), and FDA states that where a label carries no splitting information it "has not evaluated it to ensure that the two halves of a split tablet are the same in weight or drug content". So the honest answer is that the cost of a labelled starting dose of avanafil is unknown, and halving $49.48 would be making it up.

How long does each one last?

Sildenafil's label answers that and avanafil's does not. VIAGRA's section 12.2 states an effect "for up to 4 hours but the response was diminished compared to 2 hours" — a documented window, front-loaded. The STENDRA label states no duration of effect anywhere in it. The figure quoted in its place here, approximately 5 hours, is the terminal elimination half-life from section 12.3, which is a measure of how fast the drug leaves the blood rather than of how long it works, and the two are not interchangeable. Where a label is silent this page prints the silence rather than borrowing a number from somewhere else and presenting it as equivalent.

Head to head

Stendra vs Viagra

Avanafil against sildenafil, from both FDA labels. The fifteen minutes is real and so is the cleaner effect on vision. What almost nobody mentions is that the labelled starting dose of one of them has no published price at all.

Reviewed September 2026

The short answer

The speed claim is true and it is on the label. STENDRA's dosage section says it may be taken "as early as approximately 15 minutes before sexual activity" — the only lead time stated in minutes on any US PDE5 label. VIAGRA's says "approximately 1 hour before sexual activity", with a permitted window of 30 minutes to 4 hours. That is a real difference in how much planning each drug asks of you, stated by both manufacturers in the same part of the same kind of document.

The second difference is less famous and better evidenced, because two separate sections of both labels agree on it. Section 12.1 puts sildenafil's selectivity for PDE5 over the retinal enzyme PDE6 at 10-fold, and avanafil's at greater than 100-fold. Section 6.1 then reports abnormal vision in 1% at 25 mg, 2% at 50 mg, 11% at 100 mg, against 1% on placebo for sildenafil — while for avanafil no visual reaction reaches the 2% reporting threshold at any dose, and the label notes a single subject across all its trials who reported a change in colour vision.

Then the price, and it is not a footnote. At each label's own maximum dose, one avanafil tablet costs a pharmacy $49.48 on invoice and one sildenafil tablet costs $0.12762 — a factor of 388×. Eight doses a month is $395.87 against $1.02. Worse, avanafil's labelled STARTING dose of 100 mg has no published price at all: the NADAC file lists only the 200 mg tablet, and no PDE5 label permits splitting one.

What neither label offers is a conversion. There is no published equivalence between avanafil and sildenafil milligrams, and avanafil is the drug that makes the folk ratios collapse: its ladder is 50, 100 and 200 mg against sildenafil's 25, 50 and 100 mg, exactly 2× at every rung, which by the usual ladder-reading logic would make avanafil half as potent per milligram. Nobody claims that, and no circulating equivalence table includes avanafil at all.

4 of 15 dimensions are materially the same. They are marked below rather than dressed up as differences.

Avanafil

Stendra

The newest US PDE5 inhibitor and the only one whose label names a lead time in minutes. More than 100-fold selective for PDE5 over the retinal enzyme.

Dosing protocol →

Sildenafil

Viagra

The original, off patent and priced accordingly, with a documented four-hour window, a real food effect and a ten-fold PDE6 margin that shows up as colour vision changes.

Dosing protocol →

Side by side

Every row carries how well supported it is. A claim that only reflects common practice is labelled as such rather than presented as fact.

Dimension	Avanafil	Sildenafil	Basis
How long before	as early as 15 minutes before	approximately 1 hour before	labelBoth from the dosage section, so this is a like-for-like comparison of instructions rather than of pharmacokinetics. Avanafil's 15 minutes applies to the 100 mg and 200 mg doses; the label sends the 50 mg dose back to "approximately 30 minutes". Sildenafil's label permits anywhere from 30 min to 4 hr before.
Duration of effect	not stated — half-life approximately 5 hours printed in its place	up to 4 hours	labelAn honest gap on one side, not a shorter number. The STENDRA label states no duration of effect anywhere; the 5 hr figure is a terminal half-life, which is a different quantity. Sildenafil's label does state one, and adds that at 4 hours "the response was diminished compared to 2 hours".
Selectivity over the retinal enzyme (PDE6)	greater than 100-fold	10-fold	labelBoth labels print this in the same sentence form in section 12.1 and both name PDE6 as the retinal enzyme involved in phototransduction. It is one of very few mechanistic claims in this class that can be read straight across, because the two documents state it the same way.
Visual adverse reactions	Not in the ≥2% table at any dose — "1 subject" across all trials reported a change in colour vision	1% at 25 mg, 2% at 50 mg, 11% at 100 mg, against 1% on placebo	labelSildenafil's own footnote defines what its 11% means: "Mild to moderate in severity and transient, predominantly color tinge to vision, but also increased sensitivity to light, or blurred vision." These are two separate trial programmes, so the percentages are not a head-to-head — but one label has a dose-response curve for this reaction and the other has a single case report, and section 12.1 predicts exactly that.
Food effect	Peak delayed 1.2 hr, peak concentration down 39% at 200 mg — the label calls the change clinically minimal	Peak delayed 1 hr, peak concentration down 29% — the label draws no conclusion	labelThe numbers are not the difference; the conclusion drawn from them is. Avanafil's high-fat-meal effect is the LARGER of the two on peak concentration — 39% against 29% — and its label nonetheless states that "the small changes in avanafil Cmax and AUC are considered of minimal clinical significance; therefore, STENDRA may be administered with or without food". Sildenafil's label reports its 60 minutes and 29% and stops. A reader choosing on "does food matter" is choosing between two manufacturers' interpretations, not between two measurements.
Approved dose range	50–200 mg	25–100 mg	labelAvanafil's rungs are exactly 2× sildenafil's at every step — 50, 100 and 200 mg against 25, 50 and 100 mg. That is two companies choosing round numbers, not a potency measurement, and it is the clearest demonstration that ladder arithmetic cannot produce an equivalence.
Milligram equivalence between themsame	Not stated on any label, guideline or trial	Not stated on any label, guideline or trial	labelNo FDA label for any of the four PDE5 inhibitors states a dose equivalence with any other, and no published trial establishes one. Twenty milligrams of tadalafil is not "equal to" 100 mg of sildenafil in any labelled or trial sense. The only dose a label will give you for a drug is that drug's own. Avanafil is absent from every circulating equivalence table for the obvious reason: the ladder reading that produces "tadalafil 20 = sildenafil 100" would make avanafil the weakest of the four by a factor of ten against vardenafil.
Nitratessame	Absolute contraindication with organic nitrates in any form	Absolute contraindication with organic nitrates in any form	labelSection 4.1 on both, and worth reading in full rather than summarising: All four labels contraindicate concomitant use with organic nitrates or nitric oxide donors in any form — nitroglycerin, isosorbide mononitrate or dinitrate, and amyl or butyl nitrite "poppers". A PDE5 inhibitor taken with a nitrate can drop blood pressure to a dangerous level. Guanylate cyclase stimulators such as riociguat are contraindicated on all four labels as well.
Interval before a nitrate could be considered	At least 12 hours	Label states none — "it is unknown"	labelThis is the one emergency-medicine difference between them and it favours avanafil. Its label names a number: "at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered." Sildenafil's says, in full: "After patients have taken VIAGRA, it is unknown when nitrates, if necessary, can be safely administered." A stated interval is not a safe combination — but it is more than the other label offers a cardiologist at 3am.
Starting dose on an alpha-blockersame	50 mg	25 mg	labelBoth labels require the patient to be stable on the alpha-blocker first and both name a figure — 50 mg for avanafil, 25 mg for sildenafil. Each is the lowest tablet strength its own label supplies, so the two instructions are the same instruction expressed in each drug's own units.
Maximum frequencysame	Once per day	Once per day	labelOnce per day on both, in the same words. Neither label carries a licensed once-daily regimen of the kind tadalafil has, so neither offers an alternative to dosing around the event.
Headache, each label's fixed-dose table	10.5% at 200 mg against 1.7% on placebo	28% at 100 mg against 7% on placebo	labelTwo separate trial programmes with different placebo arms, so these are not a head-to-head and must not be subtracted. They are printed with their doses and placebo rates attached because a reader is entitled to see what each manufacturer reported, not because the difference is measured.
Strengths a pharmacy can actually buy	NADAC prices 200 mg — one presentation, one NDC	NADAC prices 25 mg, 50 mg, 100 mg, across dozens of NDCs	literatureThe gap between the label and the supply chain. Avanafil's labelled ladder has three rungs and the price file has one, so two of the three doses the label offers — including the starting dose — cannot be costed at all.
Cost of one labelled starting dose	Not priced — NADAC lists no 100 mg tablet	$0.10577	literatureLabel silent; SPL declares no score — so the 100 mg starting dose is not "half of the 200 mg price", it is unknown, and this page will not compute it. Every PDE5 SPL read for lib/ed-cost declares the FDA structured Score characteristic as 1, a tablet of one piece, and FDA's guidance is that an approval to split would be printed in the HOW SUPPLIED section.
Cost of one dose at the labelled maximum	$49.48 (200 mg)	$0.12762 (100 mg)	literatureA factor of 388×, computed rather than asserted. At 8 doses a month that is $395.87 against $1.02. CMS NADAC, file dated 2026-09-16 — invoice cost to a retail pharmacy, not a cash price and not a copay. For scale, branded VIAGRA at 100 mg is 655× its own generic and still costs less per tablet than avanafil.

label: Stated on the FDA label
guideline: Clinical practice guideline
literature: Published literature
practice: Common practice, not documented

Which one

Choose Avanafil if

Fifteen minutes genuinely matters to you. No other US PDE5 label states a lead time in minutes, and planning an hour ahead is the complaint sildenafil generates most.
Sildenafil gave you a colour tinge, light sensitivity or blurred vision. That reaction has a mechanism, it is dose-dependent on sildenafil's own label, and avanafil is ten times more selective away from the enzyme responsible.
You want the label that tells an emergency doctor something. Twelve hours is a number; "it is unknown" is not.
You can eat before or after without thinking about it. Avanafil's own label calls its food effect clinically minimal and permits dosing with or without food; sildenafil's reports a full hour of delay after a high-fat meal and draws no such conclusion.

Choose Sildenafil if

Cost is a real constraint. A generic sildenafil tablet costs a pharmacy a tenth of a dollar and the avanafil tablet costs fifty — and the difference is not quality, it is patent expiry.
You want a duration figure you can plan against. Sildenafil's label documents an effect to four hours; avanafil's states no duration at all.
You have used it before and it worked. Sildenafil has been on the US market since 1998 and there is more of everything about it — trials, postmarketing data, generics, prescribers who know it.
Your prescription needs to be filled anywhere, at any pharmacy. Sildenafil is stocked in three strengths across dozens of manufacturers; avanafil is one presentation from one supplier in the price file.

Do not convert between them. No label, guideline or trial states how many milligrams of avanafil correspond to how many of sildenafil, and the tempting shortcut — reading the two dose ladders across — gives an answer that makes avanafil the weaker drug, which nobody believes. If you are switching, the new drug starts at its own labelled starting dose. And note what that means for avanafil in practice: the starting dose the label recommends, 100 mg, has no price in the national acquisition-cost file, so the first prescription is one whose cost this page genuinely cannot tell you.

Frequently asked questions

Does Stendra really work in 15 minutes?: Its label says it can be taken that soon, which is not quite the same claim but is the strongest one any US PDE5 label makes. Section 2.1, verbatim: "The recommended starting dose is 100 mg. STENDRA should be taken orally as needed as early as approximately 15 minutes before sexual activity." The 15-minute figure applies to 100 mg and 200 mg; the same section sends the 50 mg dose back to "approximately 30 minutes before sexual activity". The pharmacokinetics behind it are in section 12.3: "STENDRA is rapidly absorbed after oral administration, with a median Tmax of 30 to 45 minutes in the fasted state." VIAGRA's instruction is "approximately 1 hour before", with 30 minutes to 4 hours permitted.
Is 100 mg of Stendra the same as 100 mg of Viagra?: No, and nothing published says what it is instead. No FDA label for any of the four PDE5 inhibitors states a dose equivalence with any other, and no published trial establishes one. Twenty milligrams of tadalafil is not "equal to" 100 mg of sildenafil in any labelled or trial sense. The only dose a label will give you for a drug is that drug's own. The coincidence of the number makes this pair especially misleading: avanafil's labelled ladder is 50, 100 and 200 mg and sildenafil's is 25, 50 and 100 mg, so 100 mg is the starting dose of one and the maximum of the other. Reading the ladders across would put avanafil at half sildenafil's potency per milligram, which no source claims and which is the reason avanafil appears in no circulating equivalence table. If you are switching, you start at the new drug's own labelled starting dose.
Why does Viagra make things look blue and Stendra does not?: Because of one enzyme, and both labels say so in the same place. PDE6 sits in the retina and is involved in phototransduction; sildenafil is only 10-fold more selective for its target PDE5 than for PDE6, while avanafil is greater than 100-fold. The consequence is in each label's adverse-reaction table. VIAGRA's Table 1 reports abnormal vision in 1% at 25 mg, 2% at 50 mg, 11% at 100 mg, against 1% on placebo, footnoted as "Mild to moderate in severity and transient, predominantly color tinge to vision, but also increased sensitivity to light, or blurred vision." STENDRA's ≥2% table contains no visual reaction at any dose, and its section 6.1 records that "Across all trials with any STENDRA dose, 1 subject reported a change in color vision." Two different trial programmes, so the percentages are not a head-to-head — but the mechanism and the incidence agree, which is unusual and worth something.
How long after taking one can a nitrate be given?: Twelve hours for avanafil, and sildenafil's label declines to say. STENDRA section 4.1: "In a patient who has taken STENDRA, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered." VIAGRA section 4.1: "After patients have taken VIAGRA, it is unknown when nitrates, if necessary, can be safely administered." Neither sentence makes any combination safe — both drugs are absolutely contraindicated with organic nitrates in any form, including amyl and butyl nitrite "poppers" — but if you carry a card or tell a paramedic what you have taken, one of these drugs gives them a number to work with and the other does not.
Why is Stendra so much more expensive?: Patent status, not pharmacology. Sildenafil went generic and avanafil has not. In the CMS NADAC file dated 2026-09-16, a 200 mg avanafil tablet costs a retail pharmacy $49.48 on invoice and a 100 mg generic sildenafil tablet costs $0.12762 — a factor of 388× at each label's own maximum dose, or $395.87 against $1.02 for eight doses a month. For scale, even branded VIAGRA at 100 mg, at 655× its own generic, still costs a pharmacy less per tablet than avanafil does. None of these is a price a patient pays; NADAC records invoice cost before any dispensing fee, markup or rebate.
What does a 100 mg Stendra tablet cost?: This page cannot tell you, and the reason is worth knowing. The 16 September 2026 NADAC file prices exactly one avanafil presentation — the 200 mg tablet — and there is no 100 mg row in it, even though 100 mg is the label's recommended starting dose. The obvious workaround is not available either: no PDE5 label read for this site permits splitting a tablet, every one of them declares the FDA structured Score characteristic as 1 (a tablet of one piece, rendered by DailyMed as "no score"), and FDA states that where a label carries no splitting information it "has not evaluated it to ensure that the two halves of a split tablet are the same in weight or drug content". So the honest answer is that the cost of a labelled starting dose of avanafil is unknown, and halving $49.48 would be making it up.
How long does each one last?: Sildenafil's label answers that and avanafil's does not. VIAGRA's section 12.2 states an effect "for up to 4 hours but the response was diminished compared to 2 hours" — a documented window, front-loaded. The STENDRA label states no duration of effect anywhere in it. The figure quoted in its place here, approximately 5 hours, is the terminal elimination half-life from section 12.3, which is a measure of how fast the drug leaves the blood rather than of how long it works, and the two are not interchangeable. Where a label is silent this page prints the silence rather than borrowing a number from somewhere else and presenting it as equivalent.

Sources

Next steps

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Educational reference, not medical advice. Which medication suits you is a decision for your prescriber.