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.
In other instances, some people’s eyes may be more disposed to irritation by the smoke from weed. This is particularly common if the weed is smoked in a closed space that is not properly ventilated. Very rarely, some people are allergic to weed. When this is true, the allergy may be the root cause of redness in the eye.
Some people are more inclined to experience red eyes after smoking weed. When weed is smoked regularly, however, some people may actually develop resistance to its redness-causing effects. It should also be known that the potentiality of weed to cause redness also depends on the ingredients in a particular mix of weed. Some types of weed can cause more redness than others.