Soon, in , ICOS received a patent for compound IC structurally unlike sildenafil and vardenafil , and Phase 1 clinical trials began in Cialis should not be used by patients taking nitrates such as nitroglycerin tablets or patches because the combination of these with Cialis could significantly lower blood pressure and lead to fainting or even death in some men. It works to treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Your doctor will probably tell you not to take tadalafil if you are taking street drugs containing nitrates. However, because sexual stimulation is required to initiate the local penile release of nitric oxide, tadalafil’s inhibition of PDE5 will have no effect without sexual stimulation. Take tadalafil at around the same time every day.Tadalafil 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). It is sometimes known by its generic name tadalafil, and sometimes known by its trade name, Cialis. There are also other brands of this medicine available. Learn about tadalafil (Cialis) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Prices for Tadalafil (Cialis) are as low as $ with a GoodRx coupon. See coupons. What are the side effects of Tadalafil (Cialis)? 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 in adult men.