ED Medications Compared | Sildenafil, Tadalafil, Vardenafil

The four oral medications FDA-approved for erectile dysfunction — sildenafil, tadalafil, vardenafil, and avanafil — all belong to the same class: phosphodiesterase type 5 (PDE5) inhibitors. They work by the same mechanism, they're all effective, and they share the same serious interactions. The differences come down to how fast they act, how long they last, their side effect patterns, and their cost.

This guide walks through each medication in depth, compares them in a single table, and lays out which one is typically a better fit for which situation. It draws on FDA prescribing information, the American Urological Association's ED guideline, and the National Institute of Diabetes and Digestive and Kidney Diseases.

Start an ED visit — $45 online visit Go straight to intake

The short answer

Occasional, planned sex: sildenafil is one option to discuss; a high-fat meal can delay its onset.
A longer window or a daily routine: tadalafil has both as-needed and low-dose daily regimens. A longer window means an opportunity to respond to arousal, not a continuous erection.
Another short-acting option: vardenafil has additional heart-rhythm precautions; the formulation matters.
A shorter lead time: avanafil has dose-specific instructions. No drug can be declared to have the fewest side effects by comparing rates from separate trials.
Cost: compare the exact prescribed strength and quantity. The dated ED cost comparison keeps source-linked sildenafil and tadalafil prices in one place.

How PDE5 inhibitors work

Sexual stimulation releases signals that relax muscle and increase blood flow in the penis. PDE5 inhibitors slow the breakdown of one of those signals. They help the erectile response; they do not create desire or automatically cause an erection. The best choice depends on your health, other medicines, response and preferred timing.

Side-by-side comparison

Adult ED label information; this table is not a prescription or a ranking of safety.
Feature	Sildenafil	Tadalafil	Vardenafil	Avanafil
Usual timing before sex	About 1 hour; label allows 30 minutes to 4 hours	As-needed dosing before anticipated sex; daily dosing at the same time each day	About 1 hour	About 15 minutes for 100 or 200 mg; about 30 minutes for 50 mg
Duration / routine	Shorter acting; about a 4-hour response window	As-needed effect demonstrated up to 36 hours; daily option available	Shorter acting; not a daily ED regimen	Shorter acting; not a daily ED regimen
ED strengths / regimens	25, 50 or 100 mg as needed	5, 10 or 20 mg as needed; 2.5 or 5 mg daily	Film-coated tablets: 2.5, 5, 10 or 20 mg	50, 100 or 200 mg as needed
Food	May take with or without food; a high-fat meal delays absorption	May take with or without food	May take with or without food; a high-fat meal can affect absorption	May take with or without food; a high-fat meal can delay absorption
Common effects to discuss	Headache, flushing, indigestion, congestion; visual changes	Headache, indigestion, back or muscle pain, congestion	Headache, flushing, congestion, indigestion	Headache, flushing, congestion
Distinctive consideration	Timing around a heavy meal	Longer drug exposure; daily and as-needed prescriptions are different	QT / heart-rhythm precautions; tablet formulations are not interchangeable	Dose-specific timing and important interaction limits

Usual starting doses in the labels are sildenafil 50 mg, as-needed tadalafil 10 mg, film-coated vardenafil 10 mg and avanafil 100 mg. These are reference doses, not a recommendation to start or change treatment. Older age, other medicines, kidney or liver function and side effects can require a lower dose, a longer interval or a different treatment. Do not exceed your prescribed frequency.

Sildenafil (generic Viagra)

Sildenafil suits an as-needed routine for some people. The label recommends taking it about an hour before sexual activity, and permits a window from 30 minutes to four hours before. A heavy, high-fat meal may delay the response. Sexual stimulation is still needed.

Headache, flushing, indigestion and nasal congestion are among the common effects. Color-vision changes can occur. The sildenafil side-effects guide explains trial rates and which symptoms need urgent care.

Tadalafil (generic Cialis)

Tadalafil can support an erectile response for up to 36 hours after an as-needed dose. That does not guarantee a response throughout the window or cover an entire weekend. The daily ED regimen starts at 2.5 mg in the label and may be increased to 5 mg by the prescriber; it reaches steady levels in about five days.

Daily tadalafil 5 mg is also labeled for benign prostatic hyperplasia (BPH), including ED with BPH. Urinary symptoms still need their own assessment; this indication does not mean every ED visit treats prostate disease. Back and muscle pain are described in the label. See daily versus as-needed dosing and tadalafil side effects.

Vardenafil

Vardenafil is another as-needed PDE5 inhibitor. Discussing an alternative can be reasonable when the first medicine is ineffective or poorly tolerated, but a switch does not guarantee fewer side effects. A pharmacist can confirm the available formulation and price.

Vardenafil has a specific QT-interval warning. People with congenital long-QT syndrome or taking certain antiarrhythmics should avoid it according to the label. Orally disintegrating and film-coated tablets are not interchangeable milligram for milligram.

Avanafil (Stendra)

Avanafil offers a shorter labeled lead time: approximately 15 minutes before sex for the 100 or 200 mg doses, and approximately 30 minutes for 50 mg. Response varies. It is taken no more than once daily, and important interacting medicines can make it unsuitable.

Headache, flushing and nasal congestion are common adverse reactions. Its label warns that rates from separate drug trials cannot be used to compare medicines directly; describing it as universally the safest or the one with the fewest side effects would overstate the evidence.

Who should not take PDE5 inhibitors

Nitrates and nitrites: do not combine these ED medicines with nitroglycerin, isosorbide medicines or recreational “poppers.” The combination can cause a dangerous fall in blood pressure. Do not stop prescribed heart medicine to make room for an ED pill.
Guanylate cyclase stimulators, such as riociguat: also contraindicated because of the blood-pressure risk.
Alpha blockers and other blood-pressure medicines: the prescriber must review stability, dose and the full medication list. Separating pills by a fixed number of hours does not make every combination safe.
Medicines that change drug levels: some HIV treatments, antibiotics and antifungals require dose limits, longer intervals or avoidance. Kidney or liver disease can also change which regimen is suitable.
Other ED medicines: do not combine agents, add an extra dose or switch schedules on your own. Tadalafil can remain in the body into the following day.

Sexual activity may be inadvisable with some cardiovascular conditions. Unstable chest pain, a recent heart attack or stroke, very low or uncontrolled blood pressure, and significant heart failure need individual assessment. Prior serious vision loss, retinal disease, penile curvature or conditions that increase prolonged-erection risk also need review. A past allergic reaction to the prescribed drug or its ingredients is another reason it may not be suitable.

Side effects to know

Many reported side effects are mild, but a new or severe symptom should not automatically be blamed on an ED pill. Do not assume that chest pain is indigestion or that sudden vision loss is a harmless color change.

Chest pain, collapse or severe trouble breathing: stop sexual activity and call 911. Tell responders which ED medicine you took and when. Do not take your own nitroglycerin after an ED medicine; emergency clinicians need to choose safe treatment.
An erection lasting more than four hours: go to an emergency department immediately, even if it does not hurt. A painful or unusually prolonged erection warrants prompt help sooner; do not delay care to try home remedies.
Sudden decrease or loss of vision in one or both eyes, or sudden hearing decrease or loss: stop the ED medicine and seek medical attention right away.
Swelling of the lips, tongue or throat, or trouble breathing: call 911 for a possible severe allergic reaction.

How to choose

Bring three questions to your clinician: Which medicines are safe with my health history? Which schedule fits my life? What will the exact prescription cost at my pharmacy? There is no single best pill for everyone.

If planning a dose is inconvenient, ask about the longer as-needed tadalafil window or its separate daily regimen.
If a medicine causes side effects or does not help, review timing, dose, food, arousal and other health conditions before changing treatment.
Compare prices for the actual quantity you expect to use, rather than comparing a single tablet with a month of daily treatment.

Bidwell’s ED service offers clinician review for sildenafil or tadalafil when appropriate. This four-drug guide is educational and does not promise that every medication described is available through Bidwell.

Start an ED visit Skip to intake

ED treatment near you

Frequently asked questions

Which symptoms need emergency help after an ED medicine?

Call 911 for chest pain, collapse, severe trouble breathing or a severe allergic reaction. After an ED medicine, do not take your own nitroglycerin; tell responders which medicine you took and when. An erection lasting more than four hours needs an emergency department immediately, even without pain. Stop the medicine and seek immediate medical attention for sudden vision or hearing decrease or loss.

Which ED medication is the best?

There is no single best ED medicine. Safety with your other medicines comes first; timing, response, side effects and the exact pharmacy price help guide the choice. Separate drug trials do not establish that avanafil or any other option has the fewest side effects for everyone.

How is sildenafil different from tadalafil?

Sildenafil is used as needed and has a shorter response window. Tadalafil can support a response for up to 36 hours after an as-needed dose and also has a separate low-dose daily regimen. Both require sexual stimulation. A longer window is not a continuous erection.

Can I take ED medication with alcohol?

Alcohol can make erections more difficult and can worsen dizziness or low blood pressure, particularly with tadalafil. Ask the prescriber about your medication and health history rather than assuming a fixed amount is safe. Include grapefruit products in the interaction discussion.

Who should not take ED medications?

Do not combine PDE5 inhibitors with nitrates, recreational nitrites (poppers) or guanylate cyclase stimulators such as riociguat. Heart conditions that make sexual activity unsafe, interacting medicines and other health risks need clinician assessment. Do not stop heart medicine to take an ED pill.

How much do ED medications cost?

A Bidwell ED visit is $45; medication is separate and a prescription is not guaranteed. Pharmacy prices vary by drug, strength, quantity, location and payment method. Use our dated ED cost comparison for source-linked sildenafil and tadalafil examples, then confirm the exact quote with your pharmacy.

Do ED pills cure ED?

No: they help manage erectile symptoms using the prescribed as-needed or daily regimen. Underlying contributors (cardiovascular disease, diabetes, low testosterone, medications, anxiety) still need to be addressed. Many men use ED medication while also making lifestyle changes that improve baseline function.

How long does ED medication take to work?

Sildenafil and film-coated vardenafil are usually taken about one hour before sex. Avanafil timing is dose-specific: about 15 minutes for 100 or 200 mg and about 30 minutes for 50 mg. As-needed tadalafil is taken before anticipated activity and can support a response for up to 36 hours. Daily tadalafil reaches steady levels in about five days. Follow your own prescription.

Medical disclaimer. This article is for general education and is not medical advice. It does not replace evaluation by a licensed clinician. Never combine PDE5 inhibitors with nitrate medications. If you experience chest pain, sudden vision loss, hearing loss, or an erection lasting more than 4 hours, seek emergency care.

Sources and prescribing information are linked below. Content updates and historical clinical review are dated separately at the top of the page.

Sources for this page

The medication information on this page is based on the linked prescribing information and clinical references. Your own prescription instructions may differ after individual review.

ED medication comparison