Sildenafil — what it does and how to use it safely
Sildenafil is a medicine most people know as Viagra. It helps blood flow to the penis so you can get and keep an erection when you're sexually stimulated. Doctors also prescribe lower doses under other brand names for pulmonary arterial hypertension—so the same drug can be used for different problems depending on dose and context.
How it works is simple: sildenafil relaxes blood vessels in targeted areas, improving blood flow. It won’t cause an erection by itself—you still need sexual stimulation. Expect it to start working in about 30–60 minutes and last up to four hours for most men. Individual response varies.
Typical doses and practical tips
For erectile dysfunction, common doses are 25 mg, 50 mg, or 100 mg. Many start at 50 mg, then adjust up or down based on effect and side effects. Take it on an empty stomach or after a light meal for faster action—heavy, fatty meals can slow absorption. Avoid taking more than one dose per 24 hours.
If you have kidney or liver problems, or you’re older, your doctor may suggest a lower dose. Never change dose without talking to your healthcare provider.
Side effects and safety warnings
Common side effects include headache, flushing, upset stomach, nasal congestion, and changes in vision (like a blue tint). Most are mild and short-lived. A rare but serious issue is priapism—an erection lasting longer than four hours. If that happens, seek emergency care to avoid permanent damage.
Do not take sildenafil with any nitrate medicines (often prescribed for chest pain). Combining them can cause a dangerous drop in blood pressure. Also be careful with alpha-blockers and some blood pressure drugs—your doctor can time or adjust medications to reduce risk.
Sildenafil is metabolized by the CYP3A4 enzyme. Strong CYP3A4 inhibitors such as ritonavir, some azole antifungals, and certain antibiotics can raise sildenafil levels. Grapefruit juice can increase drug levels too—avoid it around the time you take sildenafil.
If you have heart disease, recent stroke, very low blood pressure, or uncontrolled high blood pressure, talk to your doctor before using sildenafil. Same if you have a history of retinal disease or severe liver/kidney problems.
Thinking of buying sildenafil online? Use only licensed pharmacies that require a prescription. Look for clear contact info, pharmacist access, and customer reviews. Be wary of super-low prices, no-prescription offers, or pills without batch numbers—those are common red flags for counterfeit medicine. Our site has guides on choosing safe online pharmacies and spotting fakes.
Want more specifics or worried about interactions with your current meds? Ask your prescriber or pharmacist directly. They can match your health history and other drugs to the safest plan. If you try sildenafil and notice troubling side effects, stop and seek medical advice right away.
