Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Revatio (Sildenafil). If you are concerned about side effects, discuss the risks and benefits of Revatio (Sildenafil) with your doctor.

The following side effects have been reported by at least 1% of people taking Revatio (Sildenafil). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• back pain
• cough
• Diarrhea
• difficulty sleeping
• Fever
• flu-like symptoms (sudden lack of energy, fever, cough, sore throat)
• flushing
• headache
• indigestion
• muscle aches
• nausea
• nosebleeds
• pain in the extremities

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• shortness of breath
• sudden decrease or loss of hearing
• temporary memory loss

Stop taking the medication and seek immediate medical attention if any of the following occur:

• bleeding in the lungs (e.g., oozing bloody fluid from the nose and respiratory tract, bluish tint to lips and skin, rapidly worsening breathing problems)
• chest pain
• erection lasting 4 hours or longer
• seizure
• signs of a heart attack (e.g., chest pain or pressure, pain extending through shoulder and arm, nausea and vomiting, sweating)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)
• symptoms of a serious allergic reaction (such as swelling of the face, lips, tongue, or throat; skin rash; Hives; or difficulty breathing)
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
• sudden decrease or loss of vision or other vision changes

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Revatio (Sildenafil).

20 mg
Each white, film-coated, round tablet marked "RVT20" on one side and "PFIZER" on the other side, contains Revatio (Sildenafil) 20 mg. Nonmedicinal ingredients: anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose; film coating: hypromellose, lactose, titanium dioxide (E-171), and triacetin.

0.8 mg/mL solution for injection
Each mL of clear, sterile solution for injection contains 0.8 mg Revatio (Sildenafil) as Revatio (Sildenafil) citrate. Nonmedicinal ingredients: glucose and water for injection.

Do not take Revatio (Sildenafil) if you:

• are allergic to Revatio (Sildenafil) or any ingredients of the medication
• are taking Nitroglycerin (sprays, ointments, skin patches or pastes, tablets) or other nitrate medications (e.g., isosorbide dinitrate or isosorbide mononitrate) due to the risk of developing dangerously Low Blood Pressure
• have pulmonary hypertension caused by sickle cell Anemia (a red blood cell abnormality)
• have a history of vision problems related to nerve damage to the Retin A caused by decreased blood flow
• are taking the medications ketoconazole, itraconazole, ritonavir, or Riociguat
• have severely reduced liver function
• have recently had a Stroke or Heart Attack
• have an irregular heartbeat that may be life-threatening
• have unstable Angina caused by Coronary Artery Disease
• have severe low blood pressure (less than 90/50 mmHg) when starting Revatio (Sildenafil)

There may be an interaction between Revatio (Sildenafil) and any of the following:

• alcohol
• Aliskiren
• alpha-agonists (e.g., Clonidine, methyldopa)
• alpha-blockers (e.g., Alfuzosin, doxazosin, Prazosin)
• Alprostadil
• angiotensin converting enzyme inhibitors (ACEIs; Captopril, Enalapril, Ramipril)
• angiotensin receptor blockers (ARBs; e.g., Candesartan, Irbesartan, Losartan)
• Apalutamide
• Aprepitant
• "azole" antifungals (e.g., fluconazole, ketoconazole, itraconazole, Voriconazole)
• beta-adrenergic blockers (e.g., Atenolol, Propranolol, Sotalol)
• Bosentan
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carbamazepine
• ciprofloxacin
• Cobicistat
• conivaptan
• Deferasirox
• diuretics (water pills; e.g., Furosemide, Hydrochlorothiazide, triamterene)
• Dronedarone
• Enzalutamide
• grapefruit juice
• Guanfacine
• Hepatitis C antivirals (e.g., dasabuvir, ombitasvir, paritaprevir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• Hydralazine
• levodopa
• lumacaftor and Ivacaftor
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• mifepristone
• Mitotane
• Modafinil
• nitrates (e.g., nitroglycerin, isosorbide mononitrate, isosorbide dinitrate, or amyl nitrite "poppers")
• Phenobarbital
• Phenytoin
• other phosphodiesterase inhibitors (e.g., Tadalafil, Vardenafil)
• Pramipexole
• primidone
• rifabutin
• rifampin
• riociguat
• Selegiline
• St. John's wort
• Sarilumab
• siltuximab
• "statin" anticholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• Stiripentol
• Tacrolimus
• Tizanidine
• Tocilizumab
• tyrosine kinase inhibitors (e.g., Dasatinib, imatinib, Nilotinib, Sunitinib)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Revatio (Sildenafil). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Revatio (Sildenafil).

Bleeding problems: Revatio (Sildenafil) may cause your body to take longer to stop bleeding. If you have bleeding problems or a bleeding disorder, discuss with your doctor how Revatio (Sildenafil) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Blood pressure: Revatio (Sildenafil) can cause a rapid decrease in blood pressure that may add to the blood pressure-lowering effect of other medications. Tell your doctor if you are taking medications to treat high blood pressure. If you are taking medication for high blood pressure, discuss with your doctor how Revatio (Sildenafil) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Revatio (Sildenafil), and whether any special monitoring is needed.

Grapefruit juice: Grapefruit juice can increase the amount of Revatio (Sildenafil) in your blood. Do not drink grapefruit juice while taking this medication.

Heart or blood vessel problems: Revatio (Sildenafil) can make heart or blood vessel problems worse. If you have had a heart attack, stroke, or life-threatening abnormal heart rhythm within the last 6 months, or have angina, chest pain, an irregular heartbeat, or high or low blood pressure, discuss with your doctor how Revatio (Sildenafil) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Revatio (Sildenafil), and whether any special monitoring is needed.

Liver function: If you have liver problems, discuss with your doctor how Revatio (Sildenafil) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Revatio (Sildenafil), and whether any special monitoring is needed. People with severely reduced liver function should not use Revatio (Sildenafil).

Lung problems: Revatio (Sildenafil) is not recommended for people with a form of high blood pressure in the lungs called pulmonary veno-occlusive disease. If you have pulmonary veno-occlusive disease or experience sudden cough, shortness of breath, chest pain, or rapid breathing, talk to your doctor before taking Revatio (Sildenafil).

Nitrate-containing medications: Revatio (Sildenafil) should never be taken with any medications that contain nitrates. Blood pressure may suddenly drop to life-threatening levels if Revatio (Sildenafil) is taken with any nitrate-containing medication (e.g., nitroglycerin tablets, spray, or patches) or any other nitrates (e.g., isosorbide dinitrate or amyl nitrite "poppers"). Dizziness, fainting spells, heart attack, or stroke may be experienced.

Penis deformation: Men with an anatomical deformation of the penis such as angulation, cavernosal fibrosis, or Peyronie's disease should be closely monitored by their doctor while taking Revatio (Sildenafil).

Prolonged erection: Tell your doctor if you have ever had an erection that lasted longer than 4 hours, or have Sickle Cell Anemia or Leukemia, before taking Revatio (Sildenafil).

Prostate problems: Tell your doctor if you are taking medications to treat prostate problems, such as alpha-blockers (e.g., Doxazosin), as Revatio (Sildenafil) combined with these medications may cause dangerously low blood pressure.

Vision problems: If you have or have had a temporary decrease or permanent loss of vision in one or both eyes, including a condition called non-arteritic anterior ischemic optic Neuropathy (NAION), or if you have retinitis pigmentosa, tell your doctor before taking Revatio (Sildenafil).

Revatio (Sildenafil) can cause partial or complete vision loss that may be temporary or permanent. If you experience a sudden loss of vision in one or both eyes or other vision-related problems, contact your doctor immediately. If you do experience vision changes, do not drive or operate machinery until your vision returns to normal.

Pregnancy: Revatio (Sildenafil) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Revatio (Sildenafil), contact your doctor immediately.

Breast-feeding: Revatio (Sildenafil) may pass into breast milk. If you are a breast-feeding mother and are taking Revatio (Sildenafil), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children with pulmonary hypertension.