Your doctor will probably tell you not to take tadalafil if you are taking nitrates. You may even have to try more than one type of ED drug to find one that works for you. Viagra, also known by its generic name Sildenafil , is another PDE5 inhibitor that works by increasing blood flow to the penis , helping men with ED achieve and maintain penis erection. Men with BPH usually have difficulty urinating, a decreased flow of urination, hesitation at the beginning of urination, and a need to get up at night to urinate. How should this medicine be used? Talk to your doctor about which dosing schedule is right for you. BPH is caused by an enlarged prostate.1. How it works. Cialis is a brand (trade) name for tadalafil which may be used to treat erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). Cialis (tadalafil) works by blocking the action of an enzyme known as cGMP-specific phosphodiesterase type-5 (PDE-5). CIALIS for Use as Needed. Creatinine clearance 30 to 50 mL/min: A starting dose of 5 mg not more than once per day is recommended, and the maximum dose is 10 mg not more than once in every 48 hours. Creatinine clearance less than 30 mL/min or on hemodialysis: The maximum dose is 5 mg not more than once in every 72 hours [see . Cialis and Viagra are phosphodiesterase-5 (PDE5) inhibitors used for treating impotence (erectile dysfunction, or ED).; Adcirca is another brand name of tadalafil.; Common side effects of Cialis and Viagra that are similar include flushing (redness or warmth of the face, neck, or chest), headaches, stomach pain or upset, flu-like symptoms (such as stuffy .