Do not take sildenafil if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, Minitran, Deponit, Transderm-Nitro), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket), or recreational drugs such as amyl nitrate or nitrite ("poppers").
Before taking sildenafil, tell your doctor if you are using any of the following medications:
cimetidine (Tagamet, Tagamet HB);
an antibiotic such as 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);
an antifungal medication such as itraconazole (Sporanox) or ketoconazole (Nizoral);
carbamazepine (Tegretol), phenobarbital (Luminal), or phenytoin (Dilantin); or
rifampin (Rifadin, Rimactane) or rifabutin (Mycobutin).
If you are using any of these drugs, you may not be able to take sildenafil, or you may need dosage adjustments or special tests during treatment.
There may be other drugs not listed that can affect sildenafil. 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.