If you take nitrates in any form, or are on treatment for pulmonary hypertension , you should not take tadalafil. Comparison with actions of other PDE5 inhibitors[ edit ] Sildenafil and vardenafil inhibit PDE6, an enzyme found in the eye, more than tadalafil. After taking a single tablet, some of the active ingredient of Cialis remains in your body for more than 2 days. One of the first Cialis ads aired at the Super Bowl. The decision of availability is completely up to the company marketing the product.headache. indigestion. back pain. muscle pain. flushing. stuffy nose. Patients who get back pain and muscle aches usually get them 12 to 24 hours after taking Cialis and these usually go away by. Roman is a telehealth prescription service and online pharmacy that provides prescription Cialis for ED and a host of other conditions, like hair loss, cold sores, and premature ejaculation. When. For most individuals, the recommended starting dose of tadalafil is 10 mg per day taken before sexual activity (tadalafil for use as needed). Depending on the adequacy of the response or side effects, the dose may be increased to 20 mg or decreased to 5 mg a day. The effect of tadalafil may last up to 36 hours.