Tadalafil (Cialis) is prescribed for patients that have erectile dysfunction and have trouble getting a sufficient erection that would allow them to have sex. You may be initially started on a lower dose of this medication, and your dose will later be increased if the effects you have are not sufficient for your case. Never combine Tadalafil with nitrate drugs that can come in a variety of forms, including ointments, sublingual tablets etc. This drug is not intended for curing, rather than treating erectile dysfunction in males of any ages, and is therefore not expected to be efficient when you are not taking it. Tadalafil may be taken as needed (about an hour before having sex, and remains efficient during 36 hours, although this period may be different depending on a number of individual factors). This drug is also not going to prevent you from getting pregnant or decrease the risk of getting a sexually transmitted disease. If you are currently taking any herbal products, especially such as St. John's wort, tell your doctor before combining it with Tadalafil, as it may cause breakthrough bleeding. Other drugs that you need to inform your health care provider about before being prescribed Tadalafil include, but are not limited to: cyclosporine, alpha blockers, antifungals, sertraline, diltiazem, clarithromycin, isoniazid, danazol, erythromycin, metronidazole, delavirdine, dexamethasone, rifabutin, phenytoin, verapamil, medications for high blood pressure, HIV protease inhibitors, erectile dysfunction medicines, fluvoxamine, lovastatin, efavirenz, cimetidine, phenobarbital, fluoxetine, and rifampin. This list of medicines that may potentially cause interactions is not complete and you will need to discuss any drugs you are taking with your doctor or pharmacist. It is a good idea to always carry a list of all the medicines you are taking for the doctor to take a look. This can affect the dosage you will be prescribed. Make sure you take Tadalafil exactly as recommended by the doctor and avoid exceeding the dose recommended. With Tadalafil it's especially easy to keep to the rule of never taking anti-impotence medications more often than every 24 hours, as you get longer efficiency that enables you to have sex at any point during a day and a half. This is one of the reasons Tadalafil is often referred to as the "weekend pill".