Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Obesity Additionally, certain risk factors increase the risk of ED, such as smoking , lack of exercise, and drug or alcohol use. Tell your doctor if any of these symptoms are severe or do not go away: headache. From Mayo Clinic to your inbox Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. What special precautions should I follow? If you ever need emergency medical treatment for a heart problem, the health care providers who treat you will need to know when you last took tadalafil. There are two different ways to take tadalafil, either daily or on an as needed basis.Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency. What is Cialis? 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). stockcam / Getty Images What is generic Cialis? Generic Cialis is called tadalafil, which is the active ingredient in Cialis. Cialis is Food and Drug Administration (FDA) approved to.