If you need emergency medical care for a heart problem, it will be important for your health care provider to know when you last took Cialis. Because patients with recent heart attacks or stroke, heart pains angina , heart failure, uncontrolled blood pressure or uncontrolled irregular heart beats, severe liver disease, and retinal eye problems were not studied with Cialis, Cialis is not recommended for these patients. You can use Cialis on a daily basis at a lower dosage. Do not take a double dose or more than one dose per day to make up for a missed one. Patients who have a condition called “left ventricular outlet obstruction” from valvular problems or heart muscle enlargement may get side effects such as fainting or light-headedness. Also tell your doctor if you or any of your family members have or have ever had an eye disease such as retinitis pigmentosa an inherited eye condition that causes loss of vision or if you have ever had sudden severe vision loss, especially if you were told that the vision loss was caused by a blockage of blood flow to the nerves that help you see.What is Cialis? Cialis is an ED treatment that works in 30 minutes and lasts for up to 36 hours (about 1 and a half days). It contains the active ingredient tadalafil and it’s effective for 80% of men. How to take Cialis. Take one tablet at least 30 minutes before sex. The effects of Cialis can last for up to 36 hours. 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. Tadalafil (Cialis) is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). Tadalafil works by helping to relax the blood vessels in the penis, allowing blood to flow into the penis, and causing an erection.