Tadacip 20 mg is a medication used to treat erectile dysfunction (ED) in men. It contains tadalafil, which is a type of phosphodiesterase type 5 (PDE5) inhibitor. Tadalafil is also used to treat benign prostatic hyperplasia (BPH) and, in some cases, pulmonary arterial hypertension. Tadalafil blocks the enzyme PDE5, which normally breaks down cyclic guanosine monophosphate (cGMP). By inhibiting this enzyme, tadalafil allows cGMP to accumulate, leading to relaxation of the blood vessels in the penis and improved blood flow.