Sildenafil: What It Does, How to Use It, and What to Watch For
Sildenafil is a common medicine used mainly to treat erectile dysfunction (ED) and, in lower doses, certain cases of pulmonary arterial hypertension. It helps increase blood flow when you’re sexually aroused, so it won’t cause an erection on its own — sexual stimulation is still needed. That makes it a useful, fast-acting option for many people, but it also means you need to know how to use it safely.
How to use sildenafil safely
Typical starting doses for ED are 25–50 mg taken about 30–60 minutes before sex. Many people find effects for up to 4–6 hours, though that window varies. Don’t take more than one dose in 24 hours. If you’re older, have liver or kidney problems, or take certain medicines, your doctor may start you on a lower dose.
Important safety notes: never take sildenafil with any nitrate medicine (often used for chest pain) — the combination can cause a dangerous drop in blood pressure. Avoid heavy alcohol before dosing; it can reduce effectiveness and increase side effects. If you use alpha-blockers for prostate issues, your doctor will advise timing and dosing carefully to avoid low blood pressure.
Common side effects are headache, flushing, nasal congestion, indigestion and mild visual changes (blue tint or light sensitivity). Rare but serious problems include sudden hearing or vision loss and priapism (an erection lasting longer than 4 hours). If you get severe chest pain, fainting, sudden vision or hearing changes, or a painful long-lasting erection, get emergency care right away.
Interactions, special cases, and when to see a doctor
Sildenafil is broken down by liver enzymes (CYP3A4). Strong enzyme inhibitors like ritonavir or ketoconazole can raise sildenafil levels, so your doctor may cut your dose. Grapefruit and some supplements can also affect drug levels. If you have heart disease, uncontrolled high blood pressure, recent stroke, or severe liver or kidney disease, discuss risks with your clinician before using sildenafil.
Women and younger people should follow specific medical advice — sildenafil is not a general sexual stimulant and is only prescribed when clinically appropriate. For pulmonary hypertension, different dosing and monitoring apply, so use only under specialist care.
Where to buy and what to check
Always use a licensed pharmacy. In many countries sildenafil requires a prescription — that helps screen for dangerous interactions and conditions. If you’re buying online, pick pharmacies with clear contact info, verified reviews, secure payment (look for HTTPS), and a requirement for a prescription. Very low prices from unknown sellers are a red flag for fake or unsafe products.
When you get the medicine, check packaging, expiry date and tablet markings. If tablets look wrong or packaging is missing batch details, don’t use them — return or consult a pharmacist. If you’re unsure whether sildenafil is right for you or how much to take, a short call or visit to your doctor can prevent problems and make the drug work better for you.
Got questions about side effects, interactions, or where to buy safely? Ask your healthcare provider or a licensed pharmacist — they can tailor advice to your health history.
