Sildenafil in Suhagra tablets works by preventing the phosphodiesterase type 5 (PDE5) enzyme from functioning in the penis' smooth muscle cells. Sildenafil causes smooth muscle relaxation and vasodilation by blocking PDE5, which raises cyclic guanosine monophosphate (cGMP) levels in the penis. During sexual stimulation, this mechanism improves blood flow to the penile tissues, making it easier to acquire and sustain an erection.