I’m the type of person to get extremely red eyes after just one puff of weed. Some of my peers, however, seem to have even whiter whites of their eyes after smoking many bowls. So, why is there a difference and why do people get red eyes from smoking cannabis? The fact is that marijuana use, of any kind, will cause some form of redness in the sclera, also known as the white of the eye. Here’s a brief primer on what causes the redness and how to best avoid it.
Why Cannabis Causes Red Eyes?
Contrary to popular belief, the crimson hue in the eye isn’t caused by the smoke or vapor of pot. Instead, the change in eye color is caused by the chemical compound tetrahydrocannabinol (THC) found in cannabis. When consumed, THC lowers blood pressure causing blood vessels and capillaries in the eyes to dilate. Dilated ocular capillaries mean an increased blood flow making blood vessels expand into the surface of the sclera.
THC also reduces intraocular pressure, which has been helpful in the treatment of glaucoma patients. THC is used to lower the high eye pressure typical in glaucoma patients. Some studies found that high concentration THC strains can lower intraocular pressure by 25 to 30%. In general, the more THC concentration in a strain the redder the eyes will be. For glaucoma patients, edibles can provide long-lasting relief without having to keep smoking or vaping.
How Cannabis Affects Everyone Differently
A high concentration of THC is not the only factor that affects the redness in the eyes. Every strain can affect everyone differently. The differences in redness and other side effects are attributed to genetics, sex, metabolism, the frequency of consumption, and more. Heavy users can end up developing a tolerance to certain effects of THC, thereby, not getting extremely red eyes over time.
The differences in redness can also be attributed to a person’s blood pressure. People with higher blood pressure won’t experience as much redness from THC as people with lowe blood pressure. Individuals that consume high THC marijuana strains will most likely have scarlet eyes. Finally, extremely rare allergies to marijuana can cause red eyes on top of even more painful symptoms.
How to Avoid Red Eyes?
There is no way to avoid a ruby hue from marijuana containing THC. Medical patients that require THC can opt for low or no THC strains. Cannabidiol, or CBD, is another potent chemical compound found in weed that doesn’t have THC’s vasodilation properties. Developing a tolerance to THC can lead to a reduced severity in redness over time, but this method should not be depended on.
Most cannabis users end up using over-the-counter eye drops to relieve their redness, itchiness, and allergies. Most eye drops contain a decongestant like tetryzoline or tetrahydrozoline that makes dilated blood vessels constrict. After the eye drop effects wear off, however, a rebound effect can cause blood vessels to dilate even larger. For this reason, eye drops should not be used daily and instead, let the redness subside in a few hours.
Getting red eyes from marijuana is hard to avoid, especially if you’re smoking on high THC strains. Red eyes are a part of the experience that accompanies regular cannabis use, which is becoming more widely accepted. Drinking tons of water won’t make your eyes less red but will keep you hydrated, so just relax and put on some sunglasses if you have to.