Viagra (Sildenafil): What It Does, How to Use It, and What to Watch For

Viagra (sildenafil) helps most men get and keep an erection by increasing blood flow to the penis. It usually starts working in 30–60 minutes and can help for up to four hours. That doesn’t mean nonstop erections — it just makes it easier to respond to sexual stimulation.

How to take Viagra safely

Typical doses are 25 mg, 50 mg, and 100 mg. Doctors often start at 50 mg and adjust from there. Take it on an empty or light stomach — a heavy meal can delay how fast it works. Don’t take more than one dose in 24 hours.

Try a lower dose if you’re older, have kidney or liver problems, or take certain other medicines. If an erection lasts more than four hours, get emergency care — that’s priapism and can cause lasting damage.

Side effects and interactions to know

Common side effects are headache, flushing, indigestion, nasal congestion, and vision changes (like blue tint). Most are mild and go away in a few hours. Stop the drug and call a doctor if you have chest pain, sudden vision loss, or severe dizziness.

Big warning: do NOT take Viagra with nitrates (nitroglycerin or similar drugs) — the combination can drop blood pressure dangerously. Also be cautious with alpha-blockers, some blood pressure meds, and certain HIV protease inhibitors; these can change sildenafil levels and effects. Tell your prescriber about all medicines and supplements you use.

Buying, cost, and safer alternatives

Viagra is available as brand-name and generic sildenafil; generics are usually much cheaper and work the same. Always get a prescription — legitimate pharmacies require one. If you shop online, look for a licensed pharmacy, clear contact info, and verified reviews. Avoid sites that sell without a prescription or push oddly low prices.

If Viagra causes side effects or doesn’t work, other drugs like vardenafil (Levitra) or tadalafil (Cialis) might help. Each has a different onset and duration, so talk with your doctor about which fits your life and health profile.

Questions to ask your prescriber: What dose should I try first? Are my other meds safe with sildenafil? What signs mean I need immediate care? Being clear about these points makes treatment safer and more effective. If you want honest comparisons or deals, check our article on Levitra and price guides on MedsEngage for more practical tips.

Want a quick recap? Start low, avoid nitrates, buy from licensed sources, and talk openly with your doctor about other meds and health issues. That keeps Viagra working for you with fewer risks.