Why Do Eyes Turn Red After Smoking Weed?

The most well-known identifier of being high is the classic red eye look. Some users can experience a “worse” reaction than others, but it’s one of the physical markers that you just can’t avoid.

Why do you get red eyes after smoking weed? Some say it’s because of the smoke in the air—that the lingering particles are to blame for irritating your eyes. Others say that red eyes are considered to be an allergic reaction to smoking. And while both are logical and possible, there’s a more scientific reason behind it.

Red eyes are caused by a change in pressure. The main psychoactive endocannabinoid in marijuana, THC, gets into your system and causes your blood pressure to decrease. As a result, your inner-eye pressure lowers and causes blood vessels and capillaries to dilate. This allows blood flow to increase and gives small blood vessels more room to expand, resulting in what we see when we look in the mirror.

But the same scientific reasoning above is why cannabis can help glaucoma patients: A condition that causes increased pressure in your eye and on your retinal nerve. It can often lead to blindness, but researchers since the 1970s have found a positive link between marijuana and glaucoma since the drug can help lower intraocular pressure. This only lasts a few hours so it certainly isn’t a treatment, but it’s a good option for patients in pain.

Even retinal damage, one of the most common eye problems, can be improved with the use of marijuana. Studies show that cannabis has neuroprotective and antioxidant properties that encourage retinal health and prevent vision loss.

Your red eyes aren’t anything to be ashamed of; many people experience red eyes -- plus it’s just marijuana doing its medicinal thing. But it can be a burden if you’re about to walk into work or have dinner with the grandparents. Remember that it’s due to the endocannabinoids within cannabis, so it can happen with any form of consumption.

The good news is that you can do something about it. And although you may already have your own ways to remedy red eye-syndrome and being high in general, here are a few of the most common methods to avoid getting red eyes after smoking weed:

• Eye drops. Products (like Visine) are the oldest trick in the book and work within minutes since it helps to constrict blood vessels. (Remember that over-using these products can be detrimental.)
• Drink water. Unrelated to cannabis, redness in the eyes is sometimes associated with dehydration. Avoid caffeine and stay hydrated to eliminate the redness.
• Consider low THC strains. If you’re really looking to limit the amount of redness, consider a strain without high levels of CBD, CBN or THC.
• Cold compress. Cold water will soothe irritated eyes and can help decrease swelling and the amount of blood flow.
• Sunglasses. You may look ridiculous, but if nothing else works you can easily use your shades. The sun may be an irritant in and of itself, so avoid harmful rays whenever possible.
• Wait. Generally, your eyes will only stay red for a few hours so just stay where you are and wait it out.

You may have heard that consistent users have developed some form of “resistance” to experiencing red eyes. (I guess there’s only one way to find out for yourself.) But at the end of the day, it’s all harmless and red eyes are just a side-effect, so there’s no need to worry if you don't have clear eyes all of the time. Plus, it's good to know that everyone will be affected differently based on tolerance, strain types, genetics and overall health so don't count red eyes as a bad thing.