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Does CBD Make Your Eyes Red?

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"A woman using an eye dropper to drop CBD oil into a glass of tea."

Cannabis is being legalized in many states, and the use of cannabidiol (CBD) products continues to rise in popularity. As a result, many people are curious about CBD’s potential effects on the body, including the eyes. A common cliché is that cannabis will give you distinctive red eyes. But is that always true?

The fact is, CBD won’t turn your eyes red! However, other cannabinoid chemicals, such as THC, will. CBD has been a talking point around eye health for a long time, but much of the research is ongoing. As your optometrists, we aren’t here to limit how you relax, but knowing more about what these chemicals do to your eyes is vital for protecting your vision between visits for eye exams

What Are the Common Types of Cannabinoids?

There are a lot of words that get thrown around when talking about cannabis. Cannabis, marijuana, cannabinoids—it can get overwhelming. But there is a way to remember the subtle differences.

Cannabis is the general term that refers to everything that comes from the plant known as cannabis sativa. Marijuana refers to cannabis products that have substantial amounts of the chemical THC. Finally, cannabinoids are the chemical substances found in the cannabis plant, and researchers have identified over 100 cannabinoids!

Don’t worry. You don’t have to remember all of them. Instead, let’s talk about the 2 main cannabinoids: tetrahydrocannabinol (THC) and cannabidiol (CBD)


CBD is the non-mind-altering part of the cannabis plant, so it doesn’t lead to the same feeling as THC. It’s usually produced as an oil, and there’s some interesting research happening about its health and therapeutic uses.

Currently, CBD is used to treat some forms of epilepsy. It’s also sometimes used for anxiety, pain, and some muscle disorders, but there isn’t enough reliable information on its benefits for other purposes.

As for making your eyes red, CBD doesn’t dilate your blood vessels like THC does. Dilation of blood vessels in your eyes is what causes your eyes to appear bloodshot. Keep in mind that some CBD products might have trace amounts of THC, so make sure you know what you’re ingesting if you want to keep your eyes clear.


THC is the cannabinoid responsible for the change in mental state associated with marijuana use. It can also lower your blood pressure and dilate the tiny blood vessels in your eyes – making them red.

The concentration of THC typically defines the potency of cannabis products. Therefore, labels for cannabis products should show the concentration of THC per dosage, which can help you understand how much you’re taking.

"Chocolate chip cookies in a square box with a cannabis leaf placed on top."

Cannabis & Eye Health

One of the main problems optometrists run into is that while cannabis is one of the most used substances globally, its effects on the eyes are still unclear. One thing we do know is that visual acuity and peripheral vision can both be negatively affected after cannabis use.

However, CBD does have anti-inflammatory effects on the eyes. Therefore, theoretically, CBD could be used to treat inflammation caused by some eye diseases.  These conditions, however, are better treated with more well-studied chemicals, such as corticosteroid eye drops.

Some studies have demonstrated CBD’s antioxidant qualities, which can help treat macular degeneration.  This is exciting in eyecare as CBD could potentially help reduce the risk of the disease along with other potent antioxidants such as lutein and zeaxanthin.

Does Cannabis Treat Glaucoma?

It’s been a long-held idea that cannabis can relieve glaucoma symptoms. But is it true? Well, it’s complicated.

Glaucoma is a leading cause of blindness worldwide. It’s not a single condition but rather a group of conditions that cause optic nerve damage. Typically this damage is caused by increased intraocular pressure (IOP), which causes the cells in the optic nerve to die. In time, your vision can fade as your optic nerve fails to deliver information to your brain.

Despite the link between cannabis and glaucoma, there isn’t a lot of evidence supporting its medical use. This is because while THC can lower IOP in glaucoma patients, it’s only for a short time.

Current, more mainstream glaucoma eye drops are more effective.  You would otherwise have to consume enormous amounts of THC daily for the same effects.  Some people may find that an intriguing concept, but considering THC’s other effects, it isn’t exactly viable for most people.

On the other hand, CBD might not have the same side effects, but studies have shown it has either no effect or may actually increase IOP levels. While this increase won’t necessarily lead to glaucoma, it can worsen the damage glaucoma is already causing to your optic nerve.

Stay Relaxed & Safe

We’re learning more about cannabis’s benefits and drawbacks every day. So, while there are many exciting medical possibilities, it’s still best to seek support for your eye health from professionals like our team at Family Focus Eyecare!

If you’re experiencing eye irritation or problems with your vision, book an appointment with us to learn about the best ways to support your eye health, and let us help keep those red eyes clear.

Written by Dr. Joseph Rich

Dr. Joseph D. Rich moved to Columbia shortly after completing his doctorate at Southern College of Optometry in Memphis, TN. Growing up and completing his undergraduate work in biology, chemistry, and business management at the University of Central Missouri in Warrensburg, MO, Dr. Rich considers himself a full-fledged Mizzou fan and actively enjoys going to as many games as possible.
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