What it is
Viagra is a brand name for sildenafil, a PDE5 inhibitor available on prescription.
How it generally works
It supports blood flow to the penis in response to sexual stimulation.
Common side effects
Headache, flushing, indigestion, nasal congestion and visual changes have been reported.
Important warnings
Must not be combined with nitrates. May be unsuitable with certain heart, blood pressure, eye or liver conditions, and can interact with other medicines.
Consult a professional
Discuss suitability, interactions and use with a doctor or pharmacist.