How long does Viagra last? Sildenafil vs Cialis vs the other ED pills (2026)

The quick comparison

The four FDA-approved oral ED medications are all PDE5 inhibitors — they work the same way (improving blood flow to the penis in response to arousal) but differ mainly in how fast they start and how long they last. Sildenafil (Viagra) and vardenafil (Levitra) last about 4 to 6 hours. Avanafil (Stendra) is the fast starter. Tadalafil (Cialis) is the marathon, lasting up to 36 hours [1].

None of them works without sexual arousal, and all of them share the same critical safety rule about nitrates. The 'best' one is not universal — it depends on whether you value speed, duration and spontaneity, food flexibility, or a daily always-ready option.

Viagra (sildenafil): the 4-6 hour standard

Sildenafil is the original and still the reference point. It typically starts working in 30 to 60 minutes and lasts about 4 to 6 hours, with the strongest effect in the first hour or two. It is taken on-demand before sex, and a high-fat meal can slow its onset, so many people take it on a relatively empty stomach.

Within its window it does not hold an erection continuously — it makes erections possible in response to arousal. It is well studied, widely available as an inexpensive generic, and a sensible default for on-demand use when a several-hour window is enough.

Cialis (tadalafil): the 'weekend pill'

Tadalafil's defining feature is duration: a single on-demand dose can work for up to 36 hours, thanks to a much longer half-life than the others. That long window removes the clock-watching and makes sex more spontaneous across a day or two [1].

Tadalafil also uniquely comes in a low daily dose, taken every day, that keeps a steady level in your system so you are ready any time without planning around a pill — and that daily form is also used to treat benign prostatic hyperplasia (BPH) symptoms. Onset for the on-demand dose can be a little slower than sildenafil, and it is less affected by food.

Levitra (vardenafil) and Stendra (avanafil)

Vardenafil (Levitra, Staxyn) is similar to sildenafil — roughly 30 to 60 minute onset and about a 4 to 6 hour duration — and some people who do not respond well to one respond better to another, so it is a reasonable alternative. Like sildenafil, its absorption can be slowed by a heavy meal.

Avanafil (Stendra) is the newest and is built for speed: it can work in as little as about 15 to 30 minutes and is less affected by food, with a similar few-hour duration. If rapid, on-demand onset is the priority, avanafil is the one designed for it.

How to choose

Match the drug to how you want to use it. If you want on-demand use with a several-hour window and the lowest cost, sildenafil (generic) is the default. If you want spontaneity and a long window, tadalafil on-demand — or its daily low dose if you have sex often or also have BPH symptoms. If you want the fastest possible onset, avanafil. Vardenafil is a solid alternative if sildenafil underwhelms [1].

Response is individual: dose, timing relative to food, adequate arousal, and giving a drug a few tries all matter before concluding it does not work. A clinician can adjust the drug and dose — telehealth has made that an easy conversation.

The safety rule you can't skip

All PDE5 inhibitors are absolutely contraindicated with nitrates (nitroglycerin, isosorbide, and related heart medications, including recreational 'poppers'), because together they can cause a life-threatening drop in blood pressure. They also interact with alpha-blockers and certain other drugs, and are not appropriate for some heart conditions [1].

This is the reason these are prescription drugs and why buying them from unregulated online sellers is risky — counterfeit ED pills and 'male enhancement' supplements have been found spiked with undeclared PDE5 inhibitors, which is dangerous precisely because the buyer cannot know what is in them. Get them through a clinician who has reviewed your heart history and medications.

The bottom line

Viagra (sildenafil) lasts about 4 to 6 hours and starts in 30 to 60 minutes; Cialis (tadalafil) lasts up to 36 hours and enables spontaneity; vardenafil is similar to sildenafil; avanafil is the fast starter [1]. None work without arousal, and none can be combined with nitrates. Choose based on the window and onset you want, get them by prescription, and give the right drug and dose a fair trial.