The characteristic red eyes of marijuana are caused by the cannabinoid THC. Using hemp that does not contain THC, as well as extracts containing only CBD, does not produce this effect.
Why do marijuana make your eyes red?
The red eye effect is stronger in some people, weaker in others, and may also vary depending on the variety and chemical composition of cannabis. THC is responsible for redness and lowers blood pressure, which causes blood vessels and capillaries to dilate.
This also applies to the eyeballs - the capillaries in them dilate, increase blood flow to the eyes, and at the same time intraocular pressure decreases. The latter effect is considered beneficial for patients at risk of glaucoma or those already suffering from it, but THC has not yet been recognized as a drug that can be used in this disease.
Smoking cannabis and eye contact with the smoke may increase the effect of eye redness, but does not eliminate it. Red eyes may also appear with other forms of administration of hemp cannabinoids: after edible products containing THC, after taking oil and after vaporization.
How to avoid the red eye effect of cannabis?
The only sure way to avoid red eye after taking cannabis is to use varieties of the plant that do not contain THC. Other hemp cannabinoids , including CBD, do not cause eye redness. Although CBD can also lower blood pressure, it does not cause blood vessels to dilate and blood flow to the eyes, nor does it have any effect on intraocular pressure.
Ways to minimize the red eye effect of THC may be:
- avoiding smoke – changing the method of administering cannabis, e.g. vaporization,
- using eye drops that protect against dryness of the eyeball and can reduce redness,
- cold compresses for the eyes can cause blood vessels to contract and reduce redness,
- keep your body well hydrated.
Red eyes after cannabis containing THC and glaucoma treatment
Most of the data on the possibility of using THC in the treatment of glaucoma comes from the 1970s and early 1980s. In an article from 1983, you can even read about the effects of administering drops containing THC directly to human eyes.
Due to the legalization of marijuana in most places in the world, no one dealt with it for several decades. In 2022, scientists announced a newer study confirming that inhaled THC reduces intraocular pressure by an average of 15% for an average of 3 hours. This allows researchers to view THC as a viable treatment option for the disease.
However, in the case of this hemp cannabinoid, the list of side effects and consequences for those using it for medical purposes is long. It begins with the relatively long-lasting psychoactive effect of THC, the impossibility of driving under its influence, and the need for frequent (approximately 6 times a day) use to keep the pressure inside the eyeball constantly lowered for a longer period of time.
Scientists emphasize, however, that THC sets a new path for thinking about the treatment of glaucoma and there is hope that, based on the data obtained, it will be possible to find a substance that has a similar effect, but does not cause psychoactive effects. Until then, the recommended treatments for glaucoma are the conventional ones: drops, lasers and surgery.
