WHY DOES WEED MAKE YOUR EYES RED?
One of the most common effects of smoking weed is red, bloodshot eyes. It's to be expected, sure, but that doesn't answer the age-old question pondered by generations of potheads: why does weed make your eyes red?
The answer might surprise you because the truth is… your eyes turning red has nothing to do with the act of smoking at all.
THE ANSWER: LOWER BLOOD PRESSURE AND DILATED CAPILLARIES
After smoking weed, people generally experience an increase in heart rate and blood pressure. This effect is due to the plant's cannabinoids, which are chemical compounds responsible for some of the therapeutic and medicinal benefits of weed, and their initial interaction with the body. This rise in blood pressure and heart rate is comparable to normal physical activities, such as exercise or sex.
It generally takes about five to ten minutes for someone's heart rates to return to normal and for blood pressure to begin to decrease. As the blood pressure lowers, the blood vessels and capillaries dilate, including the ocular capillaries. The dilation of ocular capillaries causes increased blood flow to the eyes, which results in your eyes turning red and also reduces intraocular pressure.
In fact, according to Dr. Melanie Bone, “It's cannabis' ability to reduce intraocular pressure in the eyes that makes it a potentially viable treatment for glaucoma, a group of eye disorders that causes damage to the optic nerves which can eventually lead to blindness. It also happens to explain why your eyes become bloodshot after smoking cannabis.”
Evidence that the THC found in weed can lower intraocular pressure (IOP) is a major reason why many glaucoma patients have attempted to use medical marijuana to treat and relieve symptoms of the disease. It's important to know that some studies have contradicted or added a caveat to the claim that weed is beneficial for glaucoma. For instance, a 2018 study conducted at Indiana University found that cannabidiol (CBD), the non-intoxicating cannabinoid found in marijuana, could potentially worsen the condition by increasing eye pressure. More research into the use of weed for glaucoma treatment is needed.
DO EDIBLES MAKE YOUR EYES RED?
Similar to smoking weed, eating edibles could also make your eyes turn red. Again, this depends on the amount of THC consumed. Remember, it's not the smoke itself that makes your eyes red, but rather the ability that cannabinoids have to lower blood pressure, causing blood vessels and capillaries to dilate.
THE REDDER THE BETTER?
The amount your blood pressure is lowered and how red your eyes become depends on the amount of THC you consume.
Tetrahydrocannabinol (THC), the most common cannabinoid in weed, is responsible for the intoxication associated with smoking weed. The greater the concentration of THC in weed, the stronger the effects and the redder your eyes become.
So, red eyes can act as a sign that your weed has a high cannabinoid content (i.e., it's potent). In other words, if your eyes are noticeably bloodshot after consumption, there's a good chance you've landed yourself some highly potent weed.
Other than being a dead giveaway that you've recently smoked weed, you have no reason to be concerned about the redness of your eyes. Weed-induced eye redness will typically only last a few hours and can easily resolve if you have the right tools at your disposal.
It isn't a bad idea to have eye drops (or some sunglasses) on hand. Look for eye drop brands that are specifically designed to reduce eye redness. There are other methods that could potentially help combat weed-induced bloodshot eyes, including staying hydrated, washing your face and eyelids with cold water, or simply smoking weed with lower THC levels.