Sildenafil (patient information)

# Why is this medication prescribed
Sildenafil is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. It works by increasing blood flow to the penis during sexual stimulation. This increased blood flow can cause an erection. Sildenafil 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 to take by mouth. It should be taken as needed about 1 hour before sexual activity. However, sildenafil can be taken anytime 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. 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.
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.
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.

# Other uses for this medicine
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 or any other medications.
- do not take sildenafil if you are taking taking or have recently taken nitrates such as isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, ISMO), and nitroglycerin (Nitro-BID, Nitro-Dur, Nitroquick, Nitrostat, others). Nitrates come as tablets, sublingual (under the tongue) tablets, sprays, patches, pastes, and ointments. Ask your doctor if you are not sure whether any of your medications contain nitrates.
- do not take street drugs containing nitrates such as amyl nitrate and butyl nitrate ('poppers') while taking sildenafil.
- tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take, especially alpha blockers such as alfuzosin (Uroxatral), doxazosin (Cardura), prazosin (Minipress), tamsulosin (Flomax), and terazosin (Hytrin); amiodarone (Cordarone, Pacerone); amlodipine (Norvasc) ; certain antifungals such as fluconazole (Diflucan), griseofulvin (Fulvicin, Grifulvin, Gris-PEG), itraconazole (Sporanox), ketoconazole (Nizoral), and voriconazole (Vfend);aprepitant (Emend); carbamazepine (Carbatrol, Epitol, Tegretol);cimetidine (Tagamet, Tagamet HB); clarithromycin (Biaxin, in Prevpac); cyclosporine (Neoral, Sandimmune);delaviridine (Rescriptor);dexamethasone (Decadron, Dexpak); diltiazem (Cardizem, Dilacor, Tiazac, others); efavirenz (Sustiva); erythromycin (E.E.S., E-Mycin, Erythrocin); fluoxetine (Prozac, Sarafem); fluvoxamine (Luvox); HIV protease inhibitors including atazanavir (Reyataz), indinavir (Crixivan), lopinavir (in Kaletra),nelfinavir (Viracept), ritonavir (Norvir, in Kaletra), and saquinavir (Fortovase, Invirase); lovastatin (Advicor, Altocor, Mevacor); nefazodone; nevirapine (Viramune);other medications or devices to treat erectile dysfunction; phenobarbital; phenytoin (Dilantin, Phenytek); rifabutin (Mycobutin);rifampin (Rifadin, Rimactane); sertraline (Zoloft); troleandomycin (TAO); verapamil (Calan, Covera, Isoptin, Verelan);and zafirlukast (Accolate).
- tell your doctor what herbal products you are taking or plan to take, especially St. John's wort..
- tell your doctor if you smoke and if you have ever had an erection that lasted for several hours. Also tell your doctor if you have or have ever had a bleeding disorder, a stomach ulcer; heart, kidney, or liver disease; a heart attack; an irregular heartbeat; chest pain; a stroke; high or low blood pressure; high cholesterol; 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 or if you have ever had 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. Tell your doctor if you have ever been advised by a health care professional to avoid sexual activity for medical reasons or if you have ever experienced chest pain during sexual activity.
- you should know that sildenafil is only for use in males. Women should not take sildenafil, especially if they are or could become pregnant or are breast-feeding. If a pregnant woman takes sildenafil, she should call her doctor.
- if you are having surgery, including dental surgery, tell your doctor or dentist that you take sildenafil.
- you should know that sexual activity may be a strain on your heart, especially if you have heart disease. If you have chest pain during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise.
- tell all your health care providers that you are taking sildenafil. If you ever need emergency medical treatment for a heart problem, the health care 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.

# Side effects

## Mild side effects
Sildenafil may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- headache
- upset stomach
- diarrhea
- dizziness or lightheadedness
- flushing (feeling of warmth)
- stuffy nose

## Severe side effects
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
- changes in color vision (seeing a blue tinge on objects or having difficulty telling the difference between blue and green)
- painful erection
- prolonged erection (longer than 4 hours)
- fainting
- chest pain
- itching or burning during urination
- rash
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.
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  or by phone .

# What storage conditions are needed for this medicine
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

# In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

# 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.

# Brand names
- Viagra