Why does cannabis make eyes red? Cannactiva

Index

Red eyes are a side effect that can occur after cannabis use. What is the component of cannabis that causes red eyes? Is this effect dangerous? Is it harmful to use eye drops? Does CBD also cause red eyes? Learn more about this effect and what causes it.

Find out why cannabis use makes eyes redder

The main reason smoking or consuming cannabis causes red eyes is tetrahydrocannabinol (THC), the main psychoactive component of cannabis or marijuana. THC dilates blood vessels, including those in the eyes. This vasodilation increases blood flow, causing the veins on the surface of the eye to expand. This increase in blood vessel size is what is visually seen as red eyes.

THC, the psychoactive compound in marijuana, is what causes red eyes.

The vasodilatory effect of THC occurs not only in the eyes, but also throughout the body. This dilation of the blood vessels can lead to a decrease in blood pressure, and in some cases, this hypotension can cause dizziness or even fainting, a phenomenon known colloquially as “blancazo”.

What causes red eyes when consuming cannabis?

When cannabis is consumed, THC reduces intraocular pressure by dilating blood vessels and increasing blood flow in the eyes. This increased blood flow causes the vessels on the surface of the eye to expand, making the blood vessels in the eyes more visible and, overall, causing the characteristic eye redness.

Does consuming CBD cause red eyes?

Not all components of cannabis have the same effect. Cannabidiol (CBD) does not cause eye reddening like THC, because it does not have the vasodilation effect that THC does. On the contrary, research suggests that CBD may decrease the effects of THC.

Is it dangerous to have red eyes after consuming cannabis?

Eye redness caused by cannabis is generally harmless and temporary. However, it can be uncomfortable or annoying for some people, especially in situations where they prefer their cannabis use to be inconspicuous.

What do cannabis red eye drops do?

To relieve red eyes, some people use red eye drops, which are actually drops that reduce vasodilation and therefore redness. They may also contain lubricants, moisturizers and antihistamines to relieve dry eyes. Regular use of these products is not recommended. If what you want is to relieve dryness, there are eye drops specially designed for this purpose, without producing vasoconstriction.

How long do red eyes last after consuming cannabis?

Generally speaking, red eyes caused by cannabis use usually last between 1 to 4 hours. However, in some cases, the redness may persist up to 8 hours or more, especially with high doses or in more sensitive individuals.

Do all cannabis users produce red eyes?

Not all cannabis users experience red eyes with the same intensity. This side effect of cannabis use varies, depending on the dose and potency of the cannabis (the higher the THC content, the more intense the red eyes), the frequency of use and tolerance to the effects of THC, the individual’s genetics and health status. Regular users may develop a certain tolerance, while the red eye effect will be more pronounced in people who are not used to the effects of THC.

Red Eyes and Cannabis: The Scientific Explanation

The mechanism behind red eyes

THC produces vasodilation. This expansion of blood vessels occurs not only in the eyes, but throughout the body, which can also result in a decrease in blood pressure. THC also reduces pressure inside the eye, a property that has been harnessed medicinally to treat glaucoma. This effect can intensify eye redness.

On the other hand, some studies suggest that cannabis use may also increase the release of histamine, involved in the allergic response, which also contributes to the dilation of blood vessels and reddening of the eyes.

In addition, the effect of THC on the endocannabinoid system can reduce tear secretion, causing red eyes and increasing redness. This results in reduced lubrication of the ocular surface and thus a feeling of dryness.

Staying hydrated can help alleviate the side effects of cannabis, as dehydration can exacerbate the side effects of THC, such as cannabis-induced dry eyes and dizziness.

Industrial hemp, containing a minimal THC content, would not produce these effects, or at least not as pronounced, depending on individual sensitivity. To put it in perspective, marijuana-type cannabis, which contains THC, has a percentage of this compound ranging from 10% to 30% or more. In contrast, industrial hemp, from which CBD is obtained, has a THC percentage of less than 0.2%.

CBD to Quit the joints

Conclusion

The eye-reddening effect of cannabis consumption is caused by THC-induced vasodilation, which increases blood flow in the eye vessels. This effect is generally harmless and temporary, but can be annoying for some users.

The next time you notice red eyes after consuming cannabis, you’ll know it’s the body’s physiological response to THC. And while it may seem uncomfortable, it’s an indicator of the complex and fascinating effect of cannabis on the human body.

More information

Wang MTM, Danesh-Meyer HV. Cannabinoids and the eye. Surv Ophthalmol. 2021 Mar-Apr;66(2):327-345. doi: 10.1016/j.survophthal.2020.07.002. Epub 2020 Aug 4. PMID: 32763339.