Brand-name and generic Cialis (tadalafil) is an effective treatment for erectile dysfunction (ED) and an enlarged prostate. You can take Cialis for ED as needed before sex or on a daily basis. By controlling the enzyme, tadalafil helps to maintain an erection after the penis is stroked by increasing blood flow to the penis. Without physical action to the penis, such as that occurring during sexual intercourse, tadalafil will not work to cause an erection. Cialis (tadalafil) is a prescription tablet used for erectile dysfunction and benign prostatic hyperplasia. Learn about dosage, side effects, and more. 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. Do not split CIALIS tablets; entire dose should be taken. The recommended starting dose of CIALIS for use as needed in most patients is 10 mg, taken prior to anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. Tadalafil 20 mg is the maximum as-needed dose for ED. Learn about its uses, how long it lasts, side effects, and how to save on your prescription. For ED, Tadalafil can be taken either once per day or as needed before sexual activity, with dosages ranging from 2.5 milligrams (mg) to 20 mg. 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). Find drug information for Cialis on CVS.com, including related drug classes, side effects, dosage, and answers to frequently asked questions. Cialis is used to treat erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). Find out the recommended dosages of Cialis, how to take it, and more.