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The red-eye adverse effects from THC have been observed anecdotally, but research is limited. So the purpose of this article is to review the scientific literature.
Based on the findings, I’ll attempt to make an educated assumption (not medical advice) with six great tips on avoiding and preventing red eyes after consuming edible cannabis products, especially THC gummies.
Common Cannabis Use Side Effects That Are Specific To The Eyes
The following eye-related side effects from THC are extremely common, especially with avid cannabis users (stoners):
- bloodshot eyes/red eyes
- broken ocular capillaries
- dry eyes
- eye pressure
Side effects pertaining specifically to the eyes (like red eyes) after consuming edibles are so common everyone calls them “high eyes.”
How Fast Eyes Can Turn Red After THC Consumption
Understanding when THC edibles would cause red eyes, it’s important to consider how the body processes edible forms of Cannabis compared to other methods of consumption.
Oral ingestion takes longer for cannabinoids to reach the brain because once THC is consumed, it must be digested in the liver before entering the bloodstream. Other methods, such as vaping or smoking weed, are much faster as they don’t need to enter the bloodstream because the THC compounds go straight to the brain via inhalation.
Now, to answer the question.
When your eyes will turn red is usually when the high/psychotropic effects of THC kick in (30-45 minutes on average for THC gummies and edibles).
For more guidance on this, check out this article.
Red Eyes, THC, & Intraocular Pressure (IOP)
The research that has been conducted on this topic suggests that consuming THC edibles can cause redness in the eyes due to changes in intraocular pressure.
Intraocular pressure is a measure of the pressure within the eye and is affected by chemical imbalances inside the eye itself. Research indicates that consuming cannabis edibles can increase intraocular pressure due to an imbalance of chemicals in the ocular fluid.
This increase in intraocular pressure can lead to redness, dryness, and irritation of the eyes.
How Blood Vessels and Capillaries Are Affected by THC
THC, the primary active ingredient in Cannabis, is known to cause vasodilation. Vasodilation is the widening of blood vessels and capillaries, which can affect the appearance of redness in the eyes.
In a study of 151 people who regularly consumed cannabis edibles, researchers found that almost all participants reported significant increases in eye redness after consuming THC-infused edibles.
Of those surveyed, 65% reported their eyes being “very red” after ingesting THC edibles.
The exact mechanism by which THC causes this change in blood vessel size is not yet fully understood. However, researchers believe that it has something to do with how THC binds to cannabinoid receptors located throughout the body, including in the eyes.
As THC binds to these receptors, it triggers a series of physiological responses that lead to vasodilation. This increase in blood vessel size can result in the eyes’ red or puffy appearance.
THC-induced vasodilation is not restricted to just the eyes. It has been found to affect other body areas, including the skin and muscles.
This can lead to increased blood flow and visible flushing of the skin, as well as muscle relaxation.
Variation of Eye colors from THC use By Glaucoma Patients
Glaucoma is a medical condition affecting vision by increasing eyeball pressure. It can cause symptoms such as blurred vision, eye pain, and redness of the eyes.
Studies have shown that patients who use THC edibles may experience a reduction in intraocular pressure (IOP). This could potentially lead to improved vision among glaucoma patients. In addition, some studies have suggested that THC edibles could also change eye color.
In one study of glaucoma patients who used THC-infused edibles for three weeks, researchers observed that their eyes had become slightly redder than before the ingestion of THC edibles. The researchers concluded that the redness observed in these patients’ eyes could be due to increased blood flow resulting from decreased IOP.
The change in eye color from the study above was not permanent and disappeared after three weeks of abstaining from THC edibles. This suggests that while glaucoma patients may experience short-term changes in eye color after using THC edibles, the effects are not long-lasting.
How Long Your Eyes Will Stay Red After Eating Edibles
The duration of redness in the eyes after consuming an edible like a pot brownie, varies based on the amount and potency of Cannabis consumed as well as individual factors. Generally, the redness in the eyes due to cannabis consumption is short-lived and typically subsides within a few hours.
However, some individuals may have more pronounced redness in their eyes that persists for several hours or even days.
In addition to the amount and potency of Cannabis consumed other factors that can influence the length of time an individual’s eyes remain red include metabolism and tolerance levels. People with higher metabolic rates may find that the redness in their eyes dissipates more quickly than others, while those with lower metabolic rates may find the effects linger longer.
Similarly, individuals with higher tolerance levels for Cannabis may find that their red eyes subside more quickly than those with lower tolerance.
It is also important to consider the method of consumption when determining how long the effects of THC will last/how long eyes will remain red after consuming edible cannabis products. Ingesting edibles typically results in slower onset times and longer effects compared to inhalation, which tends to be the opposite (quicker onset, shorter lengths of effects).
6 Ways To Prevent Red Eyes After Consuming THC Gummies
One of the most common concerns for people who consume THC edibles is their red eyes. Since the active ingredient in these edible products, tetrahydrocannabinol (THC), can cause blood vessels to dilate, it can result in a reddening of the eyes.
To counteract this side effect, here are some tips on how to prevent red eyes after consuming THC gummies:
Drink plenty of water before and after consuming the edible product. Staying hydrated can help reduce the effects of THC on the blood vessels around your eyes.
Take a cold shower, perform a cold compress, or wash your face with cold water immediately after consuming the edibles. Cold water can reduce the swelling and redness caused by dilating your blood vessels.
Wear sunglasses or tinted lenses outdoors to reduce the intensity of light entering your eyes. This will help reduce the number of blood vessels that dilate in response to bright lights, thus reducing any noticeable redness in your eyes.
Consume CBD products in addition to THC edibles. Cannabidiol (CBD) has been known to reduce the effects of THC on your body and can help counteract any negative side effects like red eyes that may result from consuming THC gummies.
Over-the-counter eye drops
Limit your marijuana use and consumption of THC edibles to a lesser concentration of THC; the more you consume, the more likely your eyes will become red.
Following these tips can reduce or even prevent any redness in your eyes after consuming THC gummies.
Do Edibles Make Your Eyes Red? The answer is yes, but the severity of the redness will vary from person to person.
The consumption of THC edibles can lead to red eyes due to the dilation of blood vessels that results from the psychotropic-inducing ingredient, tetrahydrocannabinol. While this side effect is short-lived and typically subsides within a few hours, some individuals may have more pronounced symptoms that persist for several hours or even days.
To reduce or prevent any noticeable redness in your eyes, drink water and stay hydrated, take a cold shower or wash your face immediately after consumption, wear sunglasses outdoors, and consume CBD products.
Additionally, limiting your consumption of edible cannabis products can help reduce the likelihood of red eyes. Following these tips can effectively reduce or even prevent any redness in your eyes after consuming edible THC gummies.
Grotenhermen, F., & Müller-Vahl, K. (2003). The therapeutic potential of Cannabis and cannabinoids.
- Russo, E. B. (2011). Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects.
Haney M., Rabkin J., Gunderson E. (2005). Dronabinol and marijuana in HIV-positive marijuana smokers: caloric intake, mood, and sleep.
Grotenhermen F., Karus U., Lohmeyer B. (2000). Effects of substances from Cannabis sativa on the eye: a synopsis of current knowledge (in German).
Russo E. B., McPartland J. M., De Petrocellis L. (2000). Cannabis, cannabidiol, and epilepsy: potential applications for therapy?
Iseger TA, Bossong MG (2015). A systematic review of the antipsychotic properties of cannabidiol in humans
Russo EB, Guy GW (2006). A tale of two cannabinoids: the therapeutic rationale for combining tetrahydrocannabinol and cannabidiol.