Class Name(s):

• 24:08.12 Phosphodiesterase Type 5 Inhibitors

Pronunciation:

• (sil den' a fil)

Brand Name(s):

• Liqrev^®
• Revatio^®
• Viagra^®; also available generically

WHY is this medicine prescribed?

Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the lungs, causing shortness of breath, dizziness, and tiredness). Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily.

If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus (HIV).

HOW should this medicine be used?

Sildenafil comes as a tablet and suspension (liquid) to take by mouth.

If you are taking sildenafil to treat erectile dysfunction, follow your doctor's directions and the guidelines in this paragraph. Take sildenafil as needed before sexual activity. The best time to take sildenafil is about 1 hour before sexual activity, but you can take the medication any time from 4 hours to 30 minutes before sexual activity. Sildenafil usually should not be taken more than once every 24 hours. If you have certain health conditions or are taking certain medications, your doctor may tell you to take sildenafil less often. You can take sildenafil with or without food. However, if you take sildenafil with a high-fat meal, it will take longer for the medication to start to work.

If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Take sildenafil at around the same times every day.

Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take sildenafil exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Shake the liquid well for 10 seconds before each use to mix the medication evenly. Use the oral syringe provided with your medication to measure and take your dose. Follow the manufacturer's directions to use and clean the oral syringe. Do not mix the liquid with other medications or add anything to flavor the medication.

If you are taking sildenafil for erectile dysfunction, your doctor will probably start you on an average dose of sildenafil and increase or decrease your dose depending on your response to the medication. Tell your doctor if sildenafil is not working well or if you are experiencing side effects.

If you are taking sildenafil for PAH, you should know that sildenafil controls PAH but does not cure it. Continue to take sildenafil even if you feel well. Do not stop taking sildenafil without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Are there OTHER USES for this medication?

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking sildenafil,

• tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension. Ask your pharmacist for a list of the ingredients.
• Some medications should not be taken with sildenafil. Tell your doctor or pharmacist if you are taking nitrates (medications for chest pain) such as isosorbide dinitrate (Isordil), isosorbide mononitrate (Monoket), and nitroglycerin (Nitromist, Nitro-Dur, Nitrostat). Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking sildenafil, please get the advice of your doctor or pharmacist.
• tell your doctor if you are taking street drugs containing nitrates ('poppers') such as amyl nitrate, amyl nitrite, or butyl nitrate while taking sildenafil. Your doctor will tell you not to take sildenafil if you are taking street drugs containing nitrates.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• you should know that sildenafil is available under the brand names Liqrev, Revatio, and Viagra. You should only be treated with one of these products at a time.
• The following nonprescription or herbal products may interact with sildenafil: cimetidine (Tagamet HB), St. John's wort. Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking sildenafil. Do not start these medications while taking sildenafil without discussing it with your healthcare provider.
• tell your doctor if you smoke, if you have had heart surgery within the last 6 months, if you have ever had an erection that lasted for more than 4 hours, and if you have recently lost a large amount of body fluids (dehydration). This can happen if you are sick with fever, diarrhea, or vomiting; sweat a lot; or do not drink enough liquids. Also tell your doctor if you have or have ever had pulmonary veno-occlusive disease (PVOD; blockage of veins in the lungs); a stomach ulcer; heart, kidney, or liver disease; a heart attack; heart failure; angina (chest pain); an irregular heartbeat; a stroke; chest pain; high or low blood pressure; high cholesterol; a bleeding disorder; blood circulation problems; blood cell problems such as sickle cell anemia (a disease of the red blood cells), multiple myeloma (cancer of the plasma cells), or leukemia (cancer of the white blood cells); conditions affecting the shape of the penis (e.g., angulation, cavernosal fibrosis, or Peyronie's disease); or diabetes. Also tell your doctor if you or any of your family members have or have ever had an eye disease such as retinitis pigmentosa (an inherited eye condition that causes loss of vision) or if you have ever had sudden severe vision loss, especially if you were told that the vision loss was caused by a blockage of blood flow to the nerves that help you see.
• if you are a woman and you are taking sildenafil to treat PAH, tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking sildenafil, call your doctor.
• if you are having surgery, including dental surgery, tell your doctor or dentist that you are taking sildenafil.
• if you are taking sildenafil to treat erectile dysfunction, tell your doctor if you have ever been advised by a healthcare professional to avoid sexual activity for medical reasons or if you have ever experienced chest pain during sexual activity. Sexual activity may be a strain on your heart, especially if you have heart disease. If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise.
• tell all your healthcare providers that you are taking sildenafil. If you ever need emergency medical treatment for a heart problem, the healthcare providers who treat you will need to know when you last took sildenafil.

What SPECIAL DIETARY instructions should I follow?

Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine.

What should I do IF I FORGET to take a dose?

If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule.

If you are taking sildenafil for PAH, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Sildenafil may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• heartburn
• diarrhea
• nausea
• flushing (feeling of warmth)
• nosebleeds
• numbness, burning, or tingling in the arms, hands, feet, or legs
• pain in muscles, back, arms, or legs
• changes in color vision (seeing a blue tinge on objects or having difficulty telling the difference between blue and green)
• sensitivity to light
• nasal congestion

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

• sudden severe loss of vision (see below for more information)
• blurred vision
• sudden decrease or loss of hearing
• ringing in ears
• dizziness or lightheadedness
• fainting
• chest pain
• worsening shortness of breath
• erection that is painful or lasts longer than 4 hours
• rash; itching; hives; difficulty breathing or swallowing; swelling of the eyes, face, throat, tongue, or lips

Some patients experienced a sudden loss of some or all of their vision after they took sildenafil or other medications that are similar to sildenafil. The vision loss was permanent in some cases. It is not known if the vision loss was caused by the medication. If you experience a sudden loss of vision while you are taking sildenafil, call your doctor immediately. Do not take any more doses of sildenafil or similar medications such as tadalafil (Cialis) or vardenafil (Levitra) until you talk to your doctor.

There have been reports of heart attack, stroke, irregular heartbeat, bleeding in the brain or lungs, high blood pressure, and sudden death in men who took sildenafil for erectile dysfunction. Most, but not all, of these people had heart problems before taking sildenafil. It is not known whether these events were caused by sildenafil, sexual activity, heart disease, or a combination of these and other causes. Talk to your doctor about the risks of taking sildenafil.

Some patients experienced a sudden decrease or loss of hearing after they took sildenafil or other medications that are similar to sildenafil. It is not known if the hearing loss was caused by the medication. If you experience a sudden loss of hearing, sometimes with ringing in the ears or dizziness, while you are taking sildenafil, call your doctor immediately. If you are taking sildenafil (Viagra) for erectile dysfunction, do not take any more doses of sildenafil (Viagra) or similar medications such as tadalafil (Cialis) or vardenafil (Levitra) until you talk to your doctor. If you are taking sildenafil (Liqrev, Revatio) for PAH, do not stop taking your medication until you talk to your doctor.

Sildenafil may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store the tablets at room temperature and away from excess heat and moisture (not in the bathroom). Store the suspension at room temperature or in a refrigerator, but do not freeze it. Dispose of any unused suspension after 60 days.

Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. http://www.upandaway.org

Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: August 15, 2023.