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Probe · sildenafil · 3 min read

How long does Viagra last at 4 hours?

At 4 hours, Eardley counted 13 of 16 men as responders after 100 mg sildenafil versus 5 of 16 after placebo when visual sexual stimulation began at that mark. The tablet in that room was 100 mg. This vault still features 25-50 mg as the start lock. This page does not add the later 8-hour or 12-hour n/N cards.

Medically reviewed by Dr. Mateo Ruiz, MD - Clinical pharmacology, Barcelona

Last reviewed

Updated

01What this vault's 25-50 mg still inherits

Forest-green still life: four-hour mark on a dark clock, blue tablet beside it

The counselling talk for 25 mg or 50 mg still uses a roughly 4-hour working window and a plasma half-life near 4 hours.

When to swallow sits on about one hour, window to 4. The sildenafil 25-50 mg vault keeps 25-50 mg as the featured start.

02Why the tablet was 100 mg in that room

The duration arm used 100 mg. That is the labelled ceiling, not the usual start. Most men still begin at 50 mg. 25 mg is the consider-start on the same insert.

Do not read 13 of 16 as a 50 mg promise. It is a 100 mg clock in a small crossover.

03Why later hour studies stay off this page

Other protocols looked at 8 hours and 12 hours after 100 mg. Those n/N cards are a different job. Gluing them here would mix two clocks.

If a couple is planning past midnight after an early swallow, that is a class conversation, not a second Eardley table.

04How 13 of 16 compared with placebo

Five of 16 men also met the responder rule on placebo at 4 hours. The labelled claim is the difference, not a 100 percent night. Arousal was part of the method.

This page will not add a second hour's n/N from a later protocol.

05When the 4-hour counselling talk is enough

For a 50 mg start, plan the hour, keep the night inside a 4-hour band, and do not stack. Eardley's 13 of 16 is why clinicians still mention 4 hours as a working mark on the 100 mg ceiling tablet.

Once per day still caps the calendar. A late 4-hour attempt is not a second 50 mg.

06What Eardley counted at 4 hours

When visual sexual stimulation started 4 hours after dosing, 13 of 16 men on sildenafil met the responder definition versus 5 of 16 on placebo (Eardley et al., Br J Clin Pharmacol 2002). n/N and the percent sit in that one sentence: 13/16 (81%) versus 5/16 (31%).

Median duration of grade 3 or 4 erections at that mark was 5.0 minutes on sildenafil versus 0 minutes on placebo.

Sources

  1. Eardley I et al. Onset and duration of action of sildenafil. Br J Clin Pharmacol. 2002;53(s1):61S-65S. 4 h: 13/16 vs 5/16 after 100 mg.
  2. DailyMed Viagra (sildenafil) prescribing information

Checked against the current label and reviewed by Dr. Mateo Ruiz. See Probe, Assay, Glow-check, Seal.

Vault consult

Answers follow the U.S. Viagra label.

Ines D. Does 13 of 16 mean 50 mg lasts 4 hours for everyone?

Vault reply

No. That n/N is 100 mg in Eardley's 4-hour room. 50 mg is still the usual start. The counselling window is often discussed out to about 4 hours.

Craig W. What were the 8-hour numbers?

Vault reply

This page stays on the 4-hour count. It does not add 8-hour or 12-hour n/N from other protocols.

Yara L. Placebo was 5 of 16. So some nights work anyway?

Vault reply

Five of 16 met the responder rule on placebo at 4 hours. The labelled story is the gap, not a guarantee.

Before you start, stop, or change any medicine, speak with your prescriber or pharmacist - they hold your chart, this vault card does not. Open the vault disclaimer.