ED can be caused by many different things, but very often it is caused by a lack of blood flow to the tissues of the penis. The typical main objective of any ED treatment is to increase nitric oxide in the blood vessels to cause blood vessel dilation which, in turn, causes increased blood flow and an erection. Occasionally natural blood vessel dilators like L-arginine may be effective. There are herbs like Epimedium sp. that also can contribute to improved erections. However, as a whole, natural treatments have not been shown to be as effective as medications like sildenafil or tadalafil. While some natural treatments may be ultimately effective in improving erections, none of them have been shown to work as acutely as oral ED meds like sildenafil or tadalafil.