Why Marijuana Makes Your Eyes Red

Ever wonder about Red Eye? Cannabis makes your eyes red because THC, the plant’s main psychoactive chemical, lowers blood pressure which then causes blood vessels and capillaries to dilate. When the capillaries, or fine branching blood vessels, in the eyes dilate, more blood flows to the eyes. This causes the eyes to look red, and incidentally also decreases intraocular pressure. That’s why cannabis is such a well-known treatment for glaucoma.

The more THC you have in your system, the more likely your eyes are going to become red. So if you smoke a low-THC strain of cannabis or take a CBD-only tincture, your eyes will likely stay white.

