Cialis (tadalafil) is a prescription tablet used for erectile dysfunction and benign prostatic hyperplasia. Learn about dosage, side effects, and more. Cialis (tadalafil) is a prescription medication for erectile dysfunction (ED). It usually starts working within 30 minutes but can take up to 2 hours to fully set in. Be sure to follow your recommended Cialis dosage, whether you’re taking it every day or as needed. Cialis relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate). Tadalafil Common brands: Cialis, Cialis Together, Adcirca Tadalafil is a medicine mainly used to treat erection problems. You can buy it from a pharmacy after speaking with a pharmacist, but it's mostly available with a prescription. If you take tadalafil for pulmonary arterial hypertension, do not take Cialis® or other PDE5 inhibitors, including sildenafil (Revatio® or Viagra®) or vardenafil (Levitra®). Cialis is a prescription drug used to treat erectile dysfunction and benign prostatic hyperplasia. Learn about the drug’s side effects and how to manage them. Cialis (tadalafil) is used primarily to treat erectile dysfunction and symptoms of benign prostatic hyperplasia. Dosage varies based on treatment goals, ranging from daily low-dose to higher doses taken as needed. Persons surnamed Cialis objected to Eli Lilly and Company's so naming the drug, but the company has maintained that the drug's trade name is unrelated to the surname. Tadalafil is also available under the brand names Cialis and Adcirca. Typically, your doctor will start by prescribing a low dosage, then adjust it over time to reach the right amount for you. Find patient medical information for Tadalafil (Cialis, Adcirca, and others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings.