The active ingredient in Zenegra 50 mg is Sildenafil citrate. Sildenafil is a medication commonly used to treat erectile dysfunction (ED) in men. It belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors, which work by increasing blood flow to the penis during sexual stimulation, thereby facilitating an erection. It should be noted that Zenegra 50 mg or any medication containing Sildenafil should be used under the guidance of a healthcare professional.