Buy Cialis Online Tadalafil, most well-known as Cialis, is one of the most popular medicines for erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and sometimes even pulmonary hypertension. It works effectively for millions of men around the world and is renowned for its longevity. However, there are certain health conditions and situations in people that make the use of tadalafil potentially risky or outright dangerous.