Sildenafil is in a class of medications called phosphodiesterase inhibitors. Medications in this class are used to treat erectile dysfunction and pulmonary artery hypertension. Phosphodiesterase inhibitors treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection.

The success rate for sildenafil in treating ED depends on the underlying condition that caused ED but can range from 50%-85%.

Sildenafil does not cure ED, affect the libido, prevent pregnancy, or protect against sexually transmitted diseases such as human immunodeficiency virus.

Sildenafil is also used to treat pulmonary hypertension. It relaxes the smooth muscles in the walls of small blood vessels, which increases blood flow to the lungs.

Sildenafil is taken as needed before sexual activity. It is best taken approximately 1 hour before sexual activity but can be taken any time from 4 hours to 30 minutes before sexual activity.
Do not take sildenafil more than once every 24 hours.
If you are using the oral liquid, shake the bottle well for at least 10 seconds before measuring the dose. Wash the oral syringe after each use.

The usual initial dose for sildenafil is 50mg orally once a day, as needed, one hour before sexual activity.
Maintenance dose: 25-100 mg orally once a day as needed, one hour prior to sexual activity.
Usual geriatric dose for ED: 25 mg orally one hour prior to sexual activity

Sildenafil typically induces an erection within 30 minutes of taking the medication.

Sildenafil continues to work for up to four hours. Most men will see a decline in medication effect after two hours.

As with all medications for ED, you should not use sildenafil if a health care provider has ever told you that your heart is not healthy enough for sexual activity. Before taking sildenafil, notify your health care provider if you:
• Are allergic to sildenafil or any components of sildenafil. Have a condition that predisposes you to priapism (a painful erection lasting over 4 hours)
• Are taking any other prescription or nonprescription drugs or supplements as they may adversely affect how sildenafil is broken down in the body, which can lead to potentially dangerous side effects or drug interactions.
• Are taking street drugs or herbs (such as St. John’s wort), which can cause dangerous side-effects.
• Are taking any medications to treat pulmonary arterial high blood pressure. These medications and sildenafil act in the same way and can cause an overdose.
• Have heart problems, high or low blood pressure, blood circulation problems, retinitis pigmentosa, blindness in one or both eyes, bleeding problems, a stomach ulcer, pulmonary venous-occlusive disease, liver or kidney disease, a blood cell disorder, or a physical disorder of the penis called Peyronie’s disease, or if a health care provider has ever advised you not to have sexual intercourse.

No required dosing schedule is needed when using sildenafil for erectile dysfunction, except do not take more than one dose in 24 hours.

Store sildenafil in its original, closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing. Keep sildenafil in a safe location away from children.

Ask your health care provider or pharmacist how this medication should be properly disposed.

Sildenafil is sold under the brand names Revatio and Viagra.

If you take too much this medication, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.