Cialis is the generic name given to many different herbal and natural pills created to treat erectile issues. Viagra is perhaps the most well-known and one of the most popular prescription drugs for male impotence. Cialis is taken as a natural herbal alternative to Viagra. Tadalafil (TCP-5) is a drug that is used to treat BPH (an enlarged prostate; prostate cancer) as well as erectile dysfunction (ED or impotence). Other conditions can also be treated with Cialis. It's not clear what causes Cialis is effective, however studies have shown that it works.