Sildenafil is a phosphodiesterase type-5 inhibitor prescribed for erectile dysfunction. It works by increasing blood flow to the penis in response to sexual stimulation.

Take approximately one hour before sexual activity, no more than once daily. A high-fat meal can delay the onset of effect.

Common: headache, flushing, indigestion, nasal congestion, altered vision. Seek urgent care for an erection lasting more than four hours.

Absolutely contraindicated with nitrates — the combination can cause a fatal drop in blood pressure. Tell your prescriber about heart conditions and alpha-blockers.