Talk to your doctor if you experience a really strong or very weak response after taking SILAGRA 100MG and if the consequences of Silagra 100 don't last long until sexuality. Silagra 100 mg contains sildenafil citrate which belongs to a class of drugs known as PDE 5 (phosphodiesterase type 5) inhibitors. It works by blocking the action of the enzyme PDE 5 and improves blood circulation throughout the body, including the penis.