​Cialis is used to treat male sexual difficulties such as erectile dysfunction or impotence. It works by boosting blood flow to the penis, which aids in the formation and maintenance of an erection during sexual stimulation. Cialis is also used to treat prostate gland enlargement symptoms such as frequent and excessive urination. Do not use Cialis with any other medications without first seeing your doctor. Tadalafil, the generic name for Cialis, is also available.