How do ED medicines work?

All PDE 5 inhibitors work in broadly the same way. These include Viagra, sildenafil, Cialis, tadalafil, Levitra, vardenafil, and Spedra.

When you are aroused, tissues release nitric oxide, which raises levels of cyclic guanosine monophosphate (cGMP). That helps relax smooth muscle and increase blood flow into the penis. Another enzyme, phosphodiesterase 5 (PDE5), breaks down cGMP. PDE 5 inhibitor tablets block PDE5 so that, when you are sexually aroused, cGMP levels can stay higher for longer, which supports erection. They do not cause an erection without arousal, do not increase sexual desire on their own, and do not replace assessment of underlying causes of ED.