Onset of Action for Viagra (Sildenafil)
Viagra typically begins working within 30 minutes, with the American Urological Association recommending it be taken approximately one hour before sexual activity for optimal effect. 1
Timing Guidelines
- Standard recommendation: Take sildenafil approximately one hour before sexual activity for most reliable results 1
- Earliest onset: Erections can occur as early as 12 minutes after dosing in some patients 2
- Median onset time: The median time to achieve an erection leading to successful intercourse is 27 minutes (range 12-70 minutes) 2
Clinical Performance Data
Within 30 minutes of dosing:
- 71% of patients experience onset of erections 2
- 86% of eventual responders will have already responded by this timepoint 2
Within 20 minutes of dosing:
- 51% of prior sildenafil responders achieved successful intercourse 3
Important Practical Considerations
Food interactions matter: The onset time studies were conducted with patients taking sildenafil at least 2 hours after eating 3. High-fat meals can delay absorption and onset of action.
Sexual stimulation is required: The medication will not work without sexual stimulation—this is a critical counseling point that affects perceived onset time 4, 5
Duration of action: While onset is relatively rapid, the duration extends well beyond what many patients expect:
- Effective for at least 4 hours after dosing 2
- May remain effective up to 12 hours in a significant proportion of men 6
- Some patients report erectogenic effects for nearly 24 hours 7
Dosing Context
The standard starting dose is 50 mg, which can be adjusted to 25-100 mg based on efficacy and tolerability 1. Higher doses (50 mg vs 25 mg) show improved efficacy, though the benefit plateaus somewhat between 50 mg and 100 mg 8.