To treat erectile dysfunction-ED, take this medication by mouth as directed by your doctor, usually as needed. Take sildenafil at least 30 minutes, but no more than 4 hours, before sexual activity (1 hour before is most effective). Do not take more than once daily.

A high-fat meal can delay how quickly the medicine starts to work.

Dosage is based on your medical condition, response to treatment and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, over-the-counter drugs, and herbal products).

Dizziness, headache, flushing or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision or trouble talking about blue and green colors may also occur. If any of these effects persist or worsen, contact your doctor or pharmacist immediately.

To reduce the risk of dizziness and lightheadedness, stand up slowly when rising from a sitting or lying position.

Remember that this medicine has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people who use this medicine have no serious side effects.

Before taking sildenafil, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which may cause allergic reactions or other problems. Talk to your pharmacist for more information.

This medicine may make you dizzy or cause vision problems. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that requires alertness or clear vision until you can do so safely. Limit alcoholic beverages. Talk to your doctor if you use marijuana (cannabis).

Drug interactions can change how your medications work or increase the risk of serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/over-the-counter medicines and herbal products) and share it with your doctor and pharmacist. Do not start, stop or change the dose of medicine without your doctor's approval.

Sildenafil can cause a serious drop in blood pressure when used together with nitrates. A severe drop in blood pressure can lead to dizziness, fainting and rarely heart attack or stroke. Do not use sildenafil with any of the following: certain medicines used to treat chest pain/angina (nitrates such as nitroglycerin, isosorbide), recreational drugs called 'poppers' containing amyl nitrate, amyl nitrite or butyl nitrite.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. Symptoms of overdose may include severe dizziness, fainting, painful/prolonged erection.

Do not share this medicine with others. Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.