Vardenafil is a medication primarily used to treat erectile dysfunction (ED) in men. It belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil (Viagra) and tadalafil (Cialis). Vardenafil works by increasing blood flow to the penis during sexual stimulation. It achieves this by inhibiting the PDE5 enzyme, which promotes relaxation of the smooth muscle in the blood vessels of the penis, allowing for improved blood flow and erection.