Viagra Side Effects
Common Viagra (sildenafil) side effects include headache, flushing, upset stomach, and nasal congestion. Rare effects can be serious. Sildenafil must not be combined with nitrate medications. Seek emergency care for chest pain, sudden vision or hearing changes, or an erection lasting more than four hours.
Written by Virantus Editorial Team
Medically reviewed by Virantus Clinical Team · Reviewed August 2026
Last updated August 2026
Effects many men notice
Headache, facial flushing, indigestion, and a stuffy nose are among the more frequently reported effects with sildenafil (Viagra). Some men notice a brief change in color vision. These are not experienced by everyone.
Side effects can depend on dose, other medicines, and individual sensitivity. Report bothersome effects to your clinician rather than stopping and restarting without guidance.
Serious symptoms
An erection lasting more than four hours (priapism), sudden vision or hearing loss, or allergic reaction needs urgent care. Chest pain during sex is an emergency — especially because some emergency treatments interact with PDE5 inhibitors. Always tell emergency clinicians if you recently took sildenafil.
Who should not take it
People who use nitrates for chest pain, and some people with specific cardiovascular conditions, should not take sildenafil. A licensed clinician reviews your history before prescribing. This page is not a substitute for that review.
Common questions
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