Why Does Weed Make Your Eyes Red?

Why does weed make your eyes red or heavy? This is a question I get asked regularly and thought since today was 4/20 it would be appropriate to discuss.


First off, most health experts agree that smoking marijuana will damage the lungs. The bad side effect of chronic, frequent use of marijuana upon the brain is also well established. We know that marijuana has some effects on the eyes as well, but more research needs to be done to help shed some light on if weed would help out.

Why Does Weed Make Your Eyes Red

One of the most noticeable effects from marijuana is that shortly after smoking the drug your eyes get red. Tetrahydrocannabinol or the THC in marijuana lowers blood pressure which dilates the blood vessels. A dilated blood vessel will increases blood flow throughout the body. This causes the blood vessels in the eyes to become larger, causing redness or the bloodshot eyes associated with smoking weed.

The best way to get rid of the redness is not with visine that shrinks the arteries, but with an eye drop that shrinks the veins called Lumify. Here is an Amazon associate link to buy some.

Why Does Weed Make Your Eyes Feel Heavy

Again, along the same lines of why it makes your eyes red, it is the THC. That lowered blood pressure helps relax your body making it harder to open the eyes. This is also why you are more “lazy” after smoking weed. Also, the dilated blood vessels increases the amount of blood in the upper eyelid making it slightly heavier anyways.

More Research

More research is being done to examine the potential negative impact of marijuana on peripheral vision, changing eye pressure, and visual processing. Using marijuana may have potentially serious impacts on these areas.

Marijuana and Glaucoma

No weed makes your eyes talk would be complete without at least talking about weed and glaucoma. The short version is with the current research done on marijuana and glaucoma from the 1970’s until now no eye doctor would recommend marijuana for glaucoma. If you have more questions about that you can check out this YouTube video. As an Amazon associate I earn commission with qualifying purchases. If you have any other will “weed make your eyes” questions feel free to leave it in the comments and I will gladly field it.

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Dr. Thirion

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