Sildenafil: Uses, How It Works, Dosing & Safety

Thinking about sildenafil or already using it? This guide gives straight answers: what sildenafil treats, how it helps, common doses, and the safety points you need to know. No fluff—just the practical facts so you can talk with your doctor with confidence.

What sildenafil is and who uses it

Sildenafil is a medicine most people know for treating erectile dysfunction (ED). It relaxes blood vessels in the penis so blood flow increases during arousal. Doctors also prescribe a lower-dose form for pulmonary arterial hypertension (high blood pressure in the lungs). If you have ED or lung artery pressure issues, sildenafil might be on the table—talk with your clinician to see if it fits your situation.

How sildenafil works and what to expect

At its core, sildenafil blocks an enzyme called PDE5. That allows a natural chemical (cGMP) to build up and relax smooth muscle in blood vessels. For ED, take it before sexual activity—most people start feeling effects within 30–60 minutes, and it can last a few hours. Remember: sexual stimulation is still required for it to work.

Typical dosing for ED is 25 mg, 50 mg, or 100 mg taken as needed, with 50 mg often used as a starting point. Don’t take more than one dose per day. For pulmonary arterial hypertension, the usual adult dose is lower and given multiple times per day—your doctor will guide this. Older adults or people with liver/kidney problems often need a lower dose.

Common side effects are headache, flushing, indigestion, nasal congestion, and dizziness. These usually fade as the drug wears off. Less common but serious problems include a sudden drop in blood pressure, sudden vision loss, hearing loss, or an erection lasting more than 4 hours (priapism). If any of those happen, get emergency care right away.

Don’t take sildenafil with nitrates (like nitroglycerin) or with certain recreational drugs called poppers—this combo can cause life-threatening low blood pressure. Also be cautious with alpha-blockers, and tell your doctor about antifungals, HIV meds, and some antibiotics because they can raise sildenafil levels. Grapefruit juice can increase effects too.

Want to buy sildenafil online? Only use licensed pharmacies that require a valid prescription. Avoid sites that promise no-prescription delivery—those products may be fake or unsafe. If cost is a concern, ask your pharmacist about generics or discount programs and always verify dosing and pill appearance before taking any new supply.

Have other health issues like heart disease, recent stroke, or low blood pressure? Bring those up when you see your clinician. They’ll help you weigh benefits and risks and pick the right dose. If you’re unsure about interactions with your other medications, a pharmacist is a great person to ask.

Questions for your doctor: Is sildenafil safe for me? What dose should I try first? Could my other meds interact? How long should I wait between doses? Keeping these simple helps you get useful answers fast.