Indications and Usage
Sildenafil relaxes muscles and increases blood flow to particular areas of the body. Sildenafil is used to treat erectile dysfunction (impotence) and for the treatment of pulmonary arterial hypertension. Sildenafil may also be used for purposes other than those listed in this medication guide.

Important Information
A small number of patients have lost eyesight in one eye after taking sildenafil. This type of vision loss is called non-arteritic anterior ischemic optic neuropathy (NAION). NAION causes a sudden loss of eyesight because blood flow is blocked to the optic nerve. It is not clear at this time if sildenafil causes NAION. NAION also happens in patients who do not take this medicine. People who have a higher chance for NAION include those who:
- have heart disease;
- are over 50 years old;
- have diabetes;
- have high blood pressure;
- have high cholesterol;
- smoke; or
- have certain eye problems.
Stop using sildenafil if you have any loss in your eyesight and seek medical help right away. Do not take sildenafil if you are using a nitrate drug for chest pain or heart problems. Nitrates include nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, Minitran, Deponit, Transderm-Nitro, others), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket). Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Contact your doctor or seek emergency medical attention for any erection that lasts longer than 4 hours. A sustained erection can damage the penis. Refrain from further sexual activity and notify your doctor it you develop dizziness, nausea, or angina (pain, tightness, discomfort, numbness, or tingling in the chest, arms, neck, or jaw) during sexual activity. Do not take sildenafil more than once a day.

Contraindications
A small number of patients have lost eyesight in one eye after taking sildenafil. This type of vision loss is called non-arteritic anterior ischemic optic neuropathy (NAION). NAION causes a sudden loss of eyesight because blood flow is blocked to the optic nerve. It is not clear at this time if sildenafil causes NAION. NAION also happens in patients who do not take this medicine. People who have a higher chance for NAION include those who:
- have heart disease;
- are over 50 years old;
- have diabetes;
- have high blood pressure;
- have high cholesterol;
- smoke; or
- have certain eye problems.
Stop using sildenafil if you have any loss in your eyesight and seek medical help right away. Do not take sildenafil if you are using a nitrate drug for chest pain or heart problems. Nitrates include nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, Minitran, Deponit, Transderm-Nitro, others), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket). Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Before taking sildenafil, tell your doctor if you
- have had a heart attack, stroke, or life-threatening irregular heartbeats within the last six months;
- have a history of heart failure;
- have coronary artery disease;
- have angina;
- have high or low blood pressure;
- have liver problems;
- have kidney problems;
- have ever had blood problems, including sickle cell anemia or leukemia;
- have a bleeding disorder;
- have a stomach ulcer;
- have retinitis pigmentosa (an inherited condition of the eye);
- have a physical deformity of the penis such as Peyronie's disease;
- have a condition that could lead to prolonged and painful erections, such as a tumor of the bone marrow, sickle cell anemia, or leukemia; or
- are taking another medicine to treat impotence, such as alprostadil (Caverject, Muse, Edex) or yohimbine (Yocon, Yodoxin, others).
You may not be able to take sildenafil, or you may require a dosage adjustment or special monitoring during treatment if you have any of the conditions listed above. Although sildenafil is not indicated for use by women, it is in the FDA pregnancy category B. This means that sildenafil is not expected to be harmful to an unborn baby. Sildenafil should not be taken by women. It is not known whether sildenafil passes into breast milk. Sildenafil should not be taken by women. If you are over 65 years of age, you may be more likely to experience side effects from sildenafil. Your doctor may prescribe a lower dose of this medication.

Dosage and Administration
Take sildenafil exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you. Take each dose with a full glass of water. Sildenafil is usually taken when needed. It can be taken anywhere from 4 hours to one-half hour before sexual activity. Generally, it is taken 1 hour before sexual activity. The medication can help achieve an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor's instructions. Taking sildenafil after eating a high-fat meal (such as a cheeseburger and french fries) may cause the medication to take a little longer to start working. Do not take sildenafil more than once a day. If you develop dizziness, nausea, or angina (pain, tightness, discomfort, numbness, or tingling in the chest, arms, neck, or jaw) during sexual activity, refrain from further sexual activity and notify your doctor. Contact your doctor or seek emergency medical attention for any erection that lasts longer than 4 hours. A sustained erection can damage the penis. Grapefruit and grapefruit juice may interact with sildenafil. The interaction could lead to potentially adverse effects. You should discuss the use of grapefruit and grapefruit juice with your doctor. Do not increase or decrease the amount of grapefruit products in your diet without first talking to your doctor.

Possible Side Effects
If you experience any of the following serious side effects, stop taking sildenafil and seek emergency medical attention or notify your doctor immediately:
- an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);
- chest pain or an irregular heartbeat;
- swelling of the ankles or legs;
- shortness of breath;
- prolonged or severe dizziness;
- a prolonged (lasting longer than 4 hours) or painful erection; or
- dizziness, nausea, or angina (pain, tightness, discomfort, numbness, or tingling in the chest, arms, neck, or jaw).
Other, less serious side effects may be more likely to occur. Continue to take sildenafil and talk to your doctor if you experience
- flushing;
- mild dizziness;
- headache;
- nasal congestion;
- diarrhea;
- temporary blue tint in vision or other vision abnormalities; or
- itching or a rash.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

Miss a Dose
Sildenafil is used as needed, so you are not likely to miss a dose.

Overdosage
Seek emergency medical attention. Symptoms of a sildenafil overdose are not known, but are likely to include chest pain, dizziness, an irregular heartbeat, and swelling of the ankles or legs.

Drug Interaction
Do not take sildenafil if you are using a nitrate drug for chest pain or heart problems. Nitrates include nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, Minitran, Deponit, Transderm-Nitro, others), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket). Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Before taking sildenafil, tell your doctor if you are taking any of the following medications:
- any other drug used to treat impotence, such as alprostadil (Caverject, Muse, Edex) or yohimbine (Yocon, Yodoxin, others);
- the antibiotic drugs clarithromycin (Biaxin), erythromycin (E-Mycin, Eryc, Ery-Tab, others), or troleandomycin (TAO);
- an antifungal medication such as itraconazole (Sporanox) or ketoconazole (Nizoral);
- the HIV medications amprenavir (Agenerase), delavirdine (Rescriptor), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir), or saquinavir (Fortovase, Invirase);
- cimetidine (Tagamet, Tagamet HB);
- phenobarbital (Luminal);
- carbamazepine (Tegretol) or phenytoin (Dilantin); or
· rifampin (Rifadin, Rifamate) or rifabutin (Mycobutin).
You may not be able to take sildenafil, or you may require a dosage adjustment or special monitoring during treatment if you are taking any of the medicines listed above. Drugs other than those listed here may also interact with sildenafil or affect your condition. Talk to your doctor or pharmacist before taking any prescription or over-the-counter medicines, including herbal products.

Precautions
Do not take any other drug used to treat impotence, such as alprostadil (Caverject, Muse, Edex) or yohimbine (Yocon, Yodoxin, others), without first talking to your doctor. Grapefruit and grapefruit juice may interact with sildenafil. The interaction could lead to potentially adverse effects. You should discuss the use of grapefruit and grapefruit juice with your doctor. Do not increase or decrease the amount of grapefruit products in your diet without first talking to your doctor.

Storage
Store this medication at room temperature away from moisture and heat.