Sildenafil — what it does, how to use it, and how to buy it safely

Ever wondered how sildenafil works or whether you can order it online without risking fakes? This page gives straight answers: what sildenafil treats, how people usually take it, common risks, and practical tips for buying from an online pharmacy.

How sildenafil works, dose and side effects

Sildenafil is a medicine that relaxes blood vessels to help blood flow. Most people know it by the brand name Viagra. Doctors usually prescribe it for erectile dysfunction. A different formulation (Revatio) treats pulmonary arterial hypertension at lower doses.

Typical adult dose for erectile dysfunction is 25–100 mg taken about 30–60 minutes before sexual activity. It often works within half an hour and lasts up to 4–5 hours. Start low if you’re older or have liver or kidney problems, and follow your doctor’s advice. Don’t take it more than once a day.

Watch for common side effects: headache, flushing, nasal congestion, upset stomach, and changes in vision (blue tint or blurred sight). Rare but serious risks include a long-lasting erection (priapism) and sudden vision or hearing loss. If you have chest pain, fainting, or severe shortness of breath, get emergency help.

Major drug interaction to avoid: nitrates (nitroglycerin) used for chest pain. Combining them can dangerously drop your blood pressure. Also be cautious with alpha-blockers, certain antibiotics, antifungals, and strong CYP3A4 inhibitors — they can raise sildenafil levels and increase side effects. Tell your doctor about all medicines you take.

Buying sildenafil online: practical safety tips

Thinking of ordering sildenafil online? You can, but be careful. Real pharmacies ask for a valid prescription. If a site sells prescription drugs without asking, it’s a red flag. Look for clear contact info, a licensed pharmacist you can reach, and a displayed pharmacy license or verification seal.

Compare prices but avoid extremely low offers — counterfeit pills are common when prices look too good to be true. Check product photos, batch numbers, and expiry dates when your package arrives. If pills smell odd, crumble easily, or look different than described, don’t take them — return them and report the seller.

Use secure payments and prefer pharmacies with good reviews and clear shipping policies. If you’re unsure, call your regular doctor first. For people with chronic conditions, get a formal consult and a proper prescription; online symptom checks can miss important risks.

Need more detail on dosing for age, kidney or liver disease, or on how sildenafil compares to other ED treatments? Ask a pharmacist or your doctor — they can tailor advice to your health and other medications.