Does CBD Make Your Eyes Red?

The never-ending mystery of why your eyes turn red when smoking cannabis may finally be solved once and for all. And the answer to every question circles back to the same result; Vasodilation.

But before we get to that we first have to touch base on a few basics of how cannabis, hemp or marijuana, works on the body.

When you consume any form of cannabis, you are also consuming cannabinoids. Cannabinoids are the main components found in cannabis in its natural state. And unlike popular belief, the grand majority of cannabinoids are non-psychoactive. The list of non-psychoactive cannabinoids includes CBD [1].

When consumed, these cannabinoids interact with a system within your body called the Endocannabinoid System, or ECS for short [2]. The parts of the ECS that cannabinoids interact with are the endocannabinoid receptors.

Cannabinoids attach to these receptors and modify the way they work. Because these receptors have other functions they are responsible for to some degree, like sleep and rest, it is suggested that cannabinoids may change the way those functions are carried out. But that is a much deeper and broader conversation than we’ll be able to have today.

Here’s what we care about for the time being:

Many endocannabinoid receptors are located in your eyes. Which could explain why some people get red eyes when smoking cannabis.

In fact:

In research from Straiker, it is concluded that “The wide distribution of cannabinoid CB1 receptors in both the anterior eye and the retina of humans suggests that cannabinoids influence several different physiological functions in the human eye.”

And while physiological functions probably don’t include the color of your eyes directly; the question remains, does CBD make your eyes red?


Why Does Cannabis Make Your Eyes Red?

Key Takeaways


Why Does Cannabis Make Your Eyes Red?

Some studies confirm the presence of endocannabinoid receptors on vascular tissue [4]. This could explain why vasodilation occurs when cannabinoids bind to cannabinoid receptors in the eye.

By increasing the blood flow to the area, the eyeball could take on a reddened appearance. A fact that is not a secret and easily provable by anyone that has consumed THC before. According to the same study referenced above, this could be seen with CBD as well.

While THC is psychoactive and CBD is not, the red-eye effect of either of these cannabinoids is not necessarily related to their psychoactive or non-psychoactive properties. According to Járai (1999), in a study conducted on rats, certain types of CBD may cause vasodilation as well.

CBD Blood Flow

With THC the explanation is much less vague. Because THC has been used as a treatment for glaucoma for so long, it is known that its purpose is to reduce the intraocular pressure produced by the condition. One of the ways it does so is by allowing the blood inside the eye to flow more freely. Therefore making the eyes red.


The information examining the relationship between red eyes and CBD is scarce and not specific enough for us to conclusively determine whether there is a relationship between the two at all. What’s more, some of the results from studies that we did find online were rather contradictory and varied widely depending on the CBD dose used by the subjects in the studies. Because of that, we decided not to include them as part of this article.

What we do know is that CBD is capable of vasodilation and it is vasodilation in the eye area that ultimately produces red eyes in human beings. We also know that some people have experienced red eyes after consuming CBD, but many CBD products also carry THC.

In other words:

Whether or not CBD makes your eyes red is a mystery that is yet to be solved. At least from a medical perspective.

Key Takeaways

THC is still used as a treatment for ocular pressure caused by glaucoma. Making it one of the most popular treatments for the condition, and made even more popular by movies and pop culture. The reason why this is so is because of THC’s great ability to increase blood flow in the eyes. Therefore making them look bloodshot.

Because of this, people often wonder if other cannabinoids could have the same effect. In recent years, one of the most popular cannabinoids for which the question is asked has been CBD.

While CBD is not psychoactive (unlike THC), this feature has nothing to do with vasodilation. That said, there is still very little evidence to claim that CBD causes bloodshot eyes while there is a lot of evidence that allows us to understand why THC may cause them.

Hemmfy articles and blogs are meant to entertain and educate. However, we are not medical professionals and do not intend to give medical advice through them.

The knowledge around CBD and other cannabis-derived products is growing and constantly changing, as does their legal status. Hence, we recommend checking with your local authorities and a licensed physician prior to consumption.


[1] Pellati, F., Borgonetti, V., Brighenti, V., Biagi, M., Benvenuti, S., & Corsi, L. (2018). Cannabis sativa L. and Nonpsychoactive Cannabinoids: Their Chemistry and Role against Oxidative Stress, Inflammation, and Cancer. BioMed Research International, 2018, 1–15. https://doi.org/10.1155/2018/1691428

[2] Lu, H. C., & Mackie, K. (2016). An Introduction to the Endogenous Cannabinoid System. Biological Psychiatry, 79(7), 516–525. https://doi.org/10.1016/j.biopsych.2015.07.028

[3] Straiker, A. J. (1999). Localization of cannabinoid CB1 receptors in the human anterior eye and retina. PubMed. https://pubmed.ncbi.nlm.nih.gov/10476817/

[4] Cardiovascular Pharmacology of Cannabinoids. (2005). PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228270/

Simon Cartagena

Simon Cartagena is a full-time cannabis copywriter. This has led him to write for companies like Hemmfy.com where he acts as Senior Content Writer and other world-renowned cannabis publications. Simon has created Content Marketing strategies and articles that have helped company revenues increase by up to 1,000%. Simon’s goal is to help people understand cannabis in an industry where misinformation seems to be predominant.