Safety
No boxed warning. Never take it with nitrates (such as nitroglycerin or “poppers”) or riociguat: together they can cause a dangerous drop in blood pressure. Don’t combine it with another ED medicine. Get emergency care for an erection lasting more than 4 hours, and stop and call a clinician for sudden vision or hearing loss. Blood pressure can also drop with alpha-blockers, other blood pressure medicines or heavy drinking. Ask a clinician whether your heart is healthy enough for sex.
Legal status
Prescription only; FDA-approved. Sildenafil is FDA-approved for ED and sold as a generic. A pharmacy may compound it for a patient with a prescription, but compounded versions, such as chewables, are not FDA-approved.
What sildenafil is
Viagra was approved on March 27, 1998. FDA-approved generic sildenafil tablets cost a small fraction of the brand price.
FDA-approved for
- Erectile dysfunction (Viagra and its generics)
- Pulmonary arterial hypertension, at a lower dose (Revatio and its generics)
Dosing
Tablet, as needed, at most once a day, 30 minutes to 4 hours before sex. 50 mg for most men, about 1 hour before sex, then 25 mg or 100 mg based on how well it works and how well you tolerate it. Men over 65 and men on alpha-blockers may start at 25 mg. Your clinician sets the dose for you.
How well it works
In four 12- to 24-week trials of 1,797 men, 63% (25 mg), 74% (50 mg) and 82% (100 mg) reported improved erections, against 24% on placebo. Individual results vary.
Sildenafil cost
Generic sildenafil costs $1.60 to $6.25 a dose at the online providers we checked, or from $16 a month for 30 doses over 90 days (Oct 18, 2026). For a full breakdown, read Where is generic Viagra cheapest online?. For the steps, read How to get Viagra online legally.