Cialis / Tadalafil (another name as Tadanafil)is used to treat male sexual function problems(impotence or erectile dysfunction) by blocking a certain enzyme (phosphodiesterase-PDE5) in the body. In combination with sexual stimulation, tadalafil helps blood flow into the penis to achieve and maintain an erection. Tadalafil is also used to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia-BPH). Blocking PDE5 is believed to relax the smooth muscle in the prostate and bladder. This helps to relieve symptoms of BPH such as difficulty in beginning the flow of urine, weak stream, and the need to urinate frequently or urgently (including during the middle of the night). Use of this drug does not protect against sexually transmitted diseases (e.g., HIV, hepatitis B, gonorrhea, syphilis). Practice "safe sex" such as using latex condoms. Consult your doctor or pharmacist for more details. OTHER USES: This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional. Tadalafil is also available in another brand for treating high blood pressure in the lungs (pulmonary arterial hypertension). HOW TO USE: Read the patient information leaflet provided by your pharmacist and ask questions if any of the information is unclear. Take this medication by mouth with or without food as directed by your doctor. When treating symptoms of an enlarged prostate (BPH), tadalafil should be taken once a day. There are two ways that this drug may be prescribed and taken for male sexual function problems. It may be taken as needed, or it may be taken once a day every day. Your doctor will determine which is the best way for you to take this drug. Follow your doctor's directions exactly. If used regularly every day for male sexual function problems, your doctor will prescribe a low dose (usually 2.5 to 5 milligrams per day). When this drug is taken only as needed, the dosing may need to be higher. Never take more of Cialis than prescribed because you may experience serious side effects. Your doctor will adjust your dosage based on your response and other medications you may be taking (see also Drug Interactions section). Consult your doctor or pharmacist for more details. When taken as needed for male sexual function problems, take this drug at least 30 minutes before sexual activity; or use as directed by your doctor. This medication's effect on sexual ability may last up to 36 hours. Therefore, do not take more than once daily as needed. When taken regularly every day for male sexual function problems, you may attempt sexual activity at any time between your doses. Do not take more than one dose each day. If you are taking tadalafil for both male sexual function problems and an enlarged prostate (BPH), take it once a day. Do not take more than one dose each day. You may attempt sexual activity at any time between your doses. Avoid eating grapefruit or drinking grapefruit juice while being treated with this medication unless your doctor instructs you otherwise. Grapefruit juice can increase the amount of certain medications in your bloodstream. Consult your doctor or pharmacist or here for more details.