Suhagra 100 mg contains sildenafil, a phosphodiesterase type-5 (PDE5) inhibitor commonly used to treat erectile dysfunction (ED) in men. It works by increasing penile blood flow when sexual stimulation occurs, helping achieve and maintain an erection. During sexual arousal, nitric oxide activates the production of cyclic guanosine monophosphate (cGMP). This relaxes smooth muscle in penile blood vessels and allows increased blood flow. Sildenafil inhibits PDE5, the enzyme that breaks down cGMP, helping maintain the erectile response.