If you have certain health conditions or are taking certain medications, your doctor may tell you to take tadalafil less often or may prescribe a lower dose to be taken once a day. 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 is a problem with information submitted for this request. Swallow the tablet whole. Follow your doctor’s directions carefully, and ask your doctor or pharmacist to explain any part you do not understand. If you are taking tadalafil to treat erectile dysfunction, follow your doctor’s directions and the guidelines in this paragraph. Talk to your doctor about which dosing schedule is right for you. · Adults—5 milligrams (mg) once a day, taken at the same time each day, without regard for the timing of sexual activity. Children—Use is not recommended. For . Tadalafil is in a class of medications called phosphodiesterase (PDE) inhibitors. It works to treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. . It is the brand name for tadalafil, a medication also used to treat ED. Tadalafil is in a class of drugs called phosphodiesterase-5 (PDE5) inhibitors and is .