Sexual activity may be a strain on your heart, especially if you have heart disease. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. People with heart conditions should never take ED medications without consulting a doctor. Soon, in , ICOS received a patent for compound IC structurally unlike sildenafil and vardenafil , and Phase 1 clinical trials began in What Are the Symptoms of Erectile Dysfunction? One of the first Cialis ads aired at the Super Bowl.Tadalafil is available in several doses in tablet form: milligrams (mg), 5 mg, 10 mg, and 20 mg. Depending on the dose for ED, you can use it as needed before sexual activity, or take it once.  · The typical dose for once-daily Cialis for ED is milligrams (mg) to 5 mg. When used as needed for ED, the usual Cialis dose is 10 mg (with a maximum daily dose of 20 mg). The typical dose of. heart attack symptoms – chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating. Common tadalafil side effects may include: headache; flushing (warmth, redness, or tingly feeling); nausea, upset stomach; stuffy nose; or. muscle pain, back pain, pain in your arms, legs, or back. This is not a complete list of side.