Tadalafil 20 mg is a medication commonly used to treat erectile dysfunction (ED) and sometimes benign prostatic hyperplasia (BPH). It is a type of phosphodiesterase type 5 (PDE5) inhibitor, which works by increasing blood flow to the penis and helping to achieve and maintain an erection when sexually aroused. It is often taken as needed, usually 30 minutes to an hour before sexual activity. The effects can last up to 36 hours. Tadalafil can interact with other medications, particularly those used to treat heart conditions. It’s important to inform your doctor about all the medications you are taking.