Around the world, marijuana is often the most widely-used illegal drug. As there are many varieties of marijuana and marijuana is still illegal in most countries, there has been relatively little research into all the potential side effects. Currently, little is known about marijuana use in relation to erectile dysfunction. However, there are several mechanisms by which marijuana use may contribute to erectile problems.
The active ingredient in marijuana is THC. THC is a smooth-muscle relaxant. Smooth-muscle is found in the gut, artery walls, penis and various other places. The movements of smooth-muscle are not under our control. As THC relaxes the smooth-muscle in the artery walls, blood pressure and blood flow can be reduced. An erection occurs when the penis fills with blood, so if the blood pressure is insufficient, erectile dysfunction may occur. Tobacco is also connected with reducing blood flow, so if the marijuana is combined with tobacco, it may reduce blood pressure further.
Many people use marijuana for its relaxing effects. These strongly relaxed feelings may temporarily interfere with libido, preventing the user from getting an erection. More research is needed to confirm if this is the case, but many people do report marijuana having a negative effect on their sex drive.
Marijuana artificially increases the levels of dopamine in the body. After prolonged use, the body may become used to these high dopamine levels. Dopamine is also involved in sexual stimulation, so the natural levels of dopamine may no longer be enough to initiate and maintain an erection.
Cannabinoid receptors are found in the corpus cavernosum of the penis. During an erection, the corpus cavernosum is filled with blood. Evidence suggests that marijuana can interact with the cannabinoid receptors in the penis, preventing the corpus cavernosum from properly filling with blood, causing erectile dysfunction.