Tadalafil relaxes muscles and increases blood flow to particular areas of the body.
Tadalafil is used to treat erectile dysfunction (impotence).
Tadalafil may also be used for purposes other than those listed in this medication guide.
Treatment of erectile dysfunction
Take tadalafil exactly as it was prescribed for you. Do not take it in larger doses or for longer than recommended by your doctor.
Take each dose with a full glass of water.
Tadalafil can be taken with or without food.
Tadalafil is usually taken only when needed, just 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.
Do not take tadalafil more than once a day. Allow 24 hours to pass between doses.
Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.
Store this medication at room temperature away from moisture and heat.
If you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw during sexual activity, stop and call your doctor right away. You could be having a serious side effect of tadalafil.
Stop using tadalafil and get emergency medical help if you have sudden vision loss.
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using tadalafil and call your doctor at once if you have any of these serious side effects:
chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling; irregular heartbeat; swelling in your hands, ankles, or feet; shortness of breath; vision changes; feeling light-headed, fainting; or penis erection that is painful or lasts 4 hours or longer.
Before taking tadalafil, tell your doctor if you are using any of the following medications:
• cimetidine (Tagamet, Tagamet HB); erythromycin (E-Mycin, Eryc, Ery-Tab) or clarithromycin (Biaxin); doxazosin (Cardura), prazosin (Minipress), terazosin (Hytrin); HIV medicines such as amprenavir (Agenerase), tipranavir (Aptivus), darunavir (Prezista), efavirenz (Sustiva), nevirapine (Viramune), indinavir (Crixivan), saquinavir (Invirase, Fortovase), lopinavir/ ritonavir (Kaletra), fosamprenavir (Lexiva), ritonavir (Norvir), atazanavir (Reyataz), or nelfinavir (Viracept); itraconazole (Sporanox) or ketoconazole (Nizoral); carbamazepine (Tegretol), phenobarbital (Luminal), or phenytoin (Dilantin); or rifampin (Rifadin, Rimactane).
If you are using any of these drugs, you may not be able to take tadalafil, or you may need dosage adjustments or special tests during treatment.
There may be other drugs not listed that can affect tadalafil. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.
Tadalafil an oral treatment for erectile dysfunction, is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Tadalafil has the empirical formula C22H19N3O4 representing a molecular weight of 389.41. The chemical designation is pyrazino[1´,2´:1,6]pyrido[3,4-b]indole-1,4-dione. Tadalafil is available as film-coated, almond-shaped tablets for oral administration. Each tablet contains 5, 10, or 20 mg of tadalafil and the following inactive ingredients: croscarmellose sodium, hydroxypropyl cellulose, hypromellose, iron oxide, lactose monohydrate, magnesium stearate, microcrystalline cellulose, sodium lauryl sulfate, talc, titanium dioxide, and triacetin.
Tadalafil has the following structural formula: