Standard dosing at a glance

Adult dosing for erectile dysfunction
MedicationAvailable dosesUsual startTake before sexMax frequency
Sildenafil25, 50, 100 mg50 mg30–60 minutesOnce in 24 hours
Tadalafil (on demand)5, 10, 20 mg10 mgAt least 30 minutesOnce in 24 hours
Tadalafil (daily)2.5, 5 mg2.5–5 mgSame time each dayOnce daily, continuous
Vardenafil2.5, 5, 10, 20 mg10 mgAbout 60 minutesOnce in 24 hours
Vardenafil ODT10 mg only10 mgAbout 60 minutesOnce in 24 hours
Avanafil50, 100, 200 mg100 mg15–30 minutesOnce in 24 hours
This is general reference information. Your prescriber's instruction always takes precedence, and doses are reduced for older age, liver or kidney impairment, and interacting medications.

Timing and food

MedicationFood effectPractical advice
SildenafilSignificant — a high-fat meal can delay onset by an hour or moreTake on a relatively empty stomach, or allow extra time
VardenafilSignificantSame approach as sildenafil
TadalafilMinimalCan be taken with food
AvanafilModestA very heavy meal will still slow it somewhat

Adjusting the dose properly

  1. Give the starting dose a genuine trial — four to eight separate attempts, taken correctly, with actual sexual stimulation.
  2. If the response is partial, ask your prescriber about increasing to the next dose.
  3. If there is no response at all at the maximum tolerated dose after a proper trial, switching molecules is the standard next step.
  4. If side effects are the problem, a lower dose often keeps the benefit. Failing that, switch — see side effects.
  5. If two different molecules fail, that is the point to ask about urology referral and second-line options.

The most common dosing mistakes

  • Expecting it to work without arousal. These drugs amplify a signal; they do not create one.
  • Not allowing enough time. Sildenafil needs 30–60 minutes, longer after food.
  • Judging it on one attempt. First-time anxiety is near-universal and resolves with repetition.
  • Drinking heavily with it. Alcohol impairs erections independently and compounds side effects.
  • Escalating the dose without asking. Higher doses raise side effects faster than they raise efficacy.
  • Stopping too soon after a partial response. A partial response is a signal to adjust, not to give up.
FAQ

Frequently asked questions

Can I take two tablets if one does not work?
No. Exceeding the maximum dose increases side effects and risks without improving results. Speak to your prescriber about a dose increase instead.
How long before sex should I take it?
Sildenafil and vardenafil 30–60 minutes; tadalafil at least 30 minutes and often longer; avanafil 15–30 minutes. Allow extra time after a heavy meal.
Can I take ED medication every day?
Only tadalafil is licensed for daily use, at 2.5 or 5 mg. The others are for use as needed, once in 24 hours.
Does the dose need to change as I get older?
Lower starting doses are standard over 65 and with liver or kidney impairment. Your requirement may also change as other conditions or medications change.
Can I split tablets to save money?
Only if your prescriber and pharmacist have told you a particular tablet can be split safely. Some are not scored or not evenly distributed, and splitting them gives an unreliable dose.
Sources

What this is based on

We link to primary sources — clinical guidelines, regulator publications and peer-reviewed research — wherever possible. Links open on third-party sites we do not control.

  1. [01]U.S. Food and Drug Administration. Drugs@FDA — approved drug products and prescribing information.
  2. [02]American Urological Association. Erectile Dysfunction: AUA Guideline (2018).
  3. [03]MedlinePlus (National Library of Medicine). Drugs, Herbs and Supplements.