You should take tadalafil one time a day. You should only be treated with one of these products at a time. If you are a Mayo Clinic patient, this could include protected health information. By controlling the enzyme, tadalafil helps to maintain an erection after the penis is stroked by increasing blood flow to the penis. It belongs to the drug class known as PDE5 inhibitors. The enlarged prostate interferes with the normal flow of urine from the bladder and urinary tract, resulting in lower urinary tract symptoms, such as trouble urinating.Generic Cialis Tadalafil (Cialis) Switch to brand medication info_outlined Used for Benign Prostatic Hyperplasia and Erectile Dysfunction MORE expand_more Check your prescription Prescription 5mg tadalafil (Cialis) (30 tablets) edit Choose your pharmacy moses lake, WA Safeway Walgreens Rite Aid info How to use this coupon phone Need help? Drug Facts Common Brands Cialis Drug Class PDE-5 inhibitor Controlled Substance Classification Not a controlled medication Generic Status No lower-cost generic available Availability Prescription only How Tadalafil (Cialis) works Tadalafil (Cialis) is a phosphodiesterase-5 enzyme (PDE-5) inhibitor. It works by blocking PDE With Goodrx, the generic version of Cialis 20 mg (tadalafil) is about $9 for 10 tablets. The brand version is about $