How should I take Viagra?
• Take Viagra 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.
• Viagra 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 Viagra 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 Viagra 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 Viagra. 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.
• Store this medication at room temperature away from moisture and heat.

What happens if I miss a dose?
• Viagra is used as needed, so you are not likely to miss a dose.

What happens if I overdose?
• Seek emergency medical attention.
• Symptoms of a Viagra overdose are not known, but are likely to include chest pain, dizziness, an irregular heartbeat, and swelling of the ankles or legs.

What should I avoid while taking Viagra?
• 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 Viagra. 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.

What are the possible side effects of Viagra?
• If you experience any of the following serious side effects, stop taking Viagra 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 Viagra 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.

What other drugs will affect Viagra?
• Do not take Viagra 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 Viagra, 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 Viagra, 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 Viagra or affect your condition. Talk to your doctor or pharmacist before taking any prescription or over-the-counter medicines, including herbal products.

Where can I get more information?
• Your pharmacist has additional information about Viagra written for health professionals that you may read.