Sildenafil: Uses, Safety, Dosage, and Buying Tips

Sildenafil (Viagra) is the best known drug for erectile dysfunction. It helps blood flow to the penis so you can get and keep an erection when you're sexually aroused. People also use it for pulmonary arterial hypertension under different brand names and doses.

How sildenafil works is simple: it relaxes blood vessels by blocking the PDE5 enzyme. That means more blood reaches targeted areas. The effect usually starts within 30 to 60 minutes and lasts up to four hours, though response varies by person, dose, and whether you ate a big meal.

Common doses are 25 mg, 50 mg, and 100 mg. Doctors often start patients at 50 mg for ED and adjust based on effect and side effects. Never double doses in one day. Taking more won’t speed results and raises risk of headache, flushing, nasal congestion, vision changes, and low blood pressure.

Who should avoid sildenafil? Don’t take it with nitrates like nitroglycerin for chest pain — that combo can cause dangerous blood pressure drops. Also avoid it with certain blood pressure drugs and some antibiotics or antifungals that affect how the liver breaks down sildenafil. If you have severe heart disease, untreated low blood pressure, or recent stroke, check with a doctor first.

Thinking about buying sildenafil online? Use sites that require a prescription and show a licensed pharmacy address. Look for clear contact info, secure checkout, and reviews from real customers. Avoid sites offering huge discounts without asking for a prescription — fake meds are common. If pills look different from known brands or packaging is sloppy, don’t take them.

Side effects and when to call a doctor

Most side effects are mild: headache, flushing, upset stomach, and stuffy nose. Rare but serious problems include sudden vision loss, sudden hearing loss, or an erection lasting more than four hours (priapism). If any of those happen, get emergency care. If you get chest pain or severe dizziness after taking sildenafil, seek immediate help.

Alternatives and related meds

Other ED drugs include tadalafil (Cialis), vardenafil (Levitra), and avanafil (Stendra). Tadalafil lasts much longer and may be taken daily at low dose. If one drug doesn’t work or causes side effects, talk to your doctor about switching. Lifestyle changes like losing weight, quitting smoking, and managing blood sugar can also help erectile problems.

Practical tips: take sildenafil on an empty stomach for faster effect; avoid heavy fatty meals before dosing; start with a middle dose so you can adjust; store meds in a cool dry place; never share prescriptions. Always discuss interactions with your pharmacist or doctor, especially if you take heart or blood pressure medications.

This tag page links to reviews and guides on buying meds online, alternatives like tadalafil and avanafil, and personal stories about side effects. Use those posts to research options, but rely on your prescriber for final advice. If cost is an issue, ask your pharmacist about generics and patient assistance programs that can lower out-of-pocket expenses quickly and safely. Check for coupons too.