Viagra (sildenafil): quick facts and what to watch for

Viagra is the brand name for sildenafil, a pill many people use to treat erectile dysfunction (ED). It helps blood flow to the penis so an erection is possible with sexual stimulation. Sildenafil can work fast—often in 30–60 minutes—and effects usually last about 3–5 hours, though that varies by person and dose.

Here’s what matters most: know the dose that fits you, watch for drug interactions, and never mix it with nitrates. Also be careful buying pills online—fake products are common and can be dangerous.

How Viagra works and dosing

Sildenafil blocks an enzyme that limits blood flow in the penis. Doctors usually start with 50 mg taken about an hour before sex. Depending on how you respond, they may lower it to 25 mg or raise it to 100 mg. Don’t take more than one dose a day.

Timing and food matter. A heavy meal—especially high-fat—can slow how quickly it starts. Alcohol can reduce effectiveness and add side effects like dizziness. If you need longer-lasting action, drugs like tadalafil (Cialis) last much longer and might suit different needs.

Safety, side effects, and interactions

Common side effects include headache, flushing, upset stomach, nasal congestion, and mild vision changes. Most are short-lived. Rare but serious problems include priapism (an erection lasting over 4 hours) and sudden vision or hearing loss—seek emergency care if these happen.

Big safety rule: don’t take sildenafil with nitrates (nitroglycerin or similar) — the combo can cause a dangerous drop in blood pressure. Tell your doctor about heart meds, alpha-blockers for prostate issues, certain HIV or antifungal drugs, and riociguat. Grapefruit juice can raise sildenafil levels, so avoid large amounts.

If you have heart disease, low blood pressure, uncontrolled high blood pressure, severe liver disease, or recent stroke/heart attack, check with your doctor before using Viagra. Your doctor can suggest tests or safer alternatives.

Thinking of buying Viagra online? Use these quick checks: only buy from pharmacies that require a prescription, show clear contact info, use secure payment, and have real customer reviews. Avoid suspiciously cheap offers and pills sent in unlabeled packages—those are red flags for counterfeits.

If sildenafil isn’t right for you, other options include tadalafil, vardenafil, avanafil, and products like Vidalista or Kamagra in some markets. Each drug has its own timing, duration, and side-effect profile—talk with your clinician to find what fits your health and lifestyle.

Got questions about dosing, interactions, or how to find a safe online pharmacy? Ask your doctor or pharmacist. A short chat can prevent a lot of worry and keep things safe when you treat ED.