Why Can Using Cannabis Make Your Eyes Red? A Surprising Explanation

An opened jar of dried cannabis flower.

A lot of people associate smoking cannabis with overly red eyes, and you may be surprised to learn that the main reason for this effect has little to do with the smoke itself. In fact, red eyes from cannabis use can actually be a strong indicator of increased health and vitality. Here’s why.

Reasons for the Redness

For in the majority of people, it’s the THC found in cannabis and not the smoke itself that creates the red-eye effect. This is because THC binds with a receptor in your body called CB1, and there are an abundance of these type of receptors in the human eye. This binding action activates signals to lower blood pressure throughout your body, including the ‘intraocular’ pressure in your eyes. When intraocular blood pressure is lowered, your vessels open up wider, and this causes more blood to rush into your eyes.

There are also some people who are allergic to smoke, or irritated by it, and would therefore experience some kind of eye redness regardless of the type of smoke they are exposed to. A third less common reason for eye redness is an allergy to cannabis itself.

THC’s ability to lower intraocular blood pressure is actually a very positive benefit for people who are suffering from the eye disease glaucoma, a condition that affects more than 400,000 Canadians. The high pressure associated with this condition leads to optic nerve damage and eventually blindness. Cannabis therapy administered via edibles can lower this pressure for up to eight hours, which helps to slow down glaucoma’s progression.

Other Ways Cannabis Can Help Your Eyes

Besides assisting with glaucoma, ingesting the healthy compounds that are found in cannabis has been shown to help reduce your risk for a number of other detrimental conditions that can negatively affect your eyes:

  • It can protect against the most common eye disease affecting Canadians today, known as diabetic retinopathy.
  • It may significantly slow down the damage to photoreceptors, which is a key contributor to degenerative blindness.
  • It has shown promise for improving night vision and enhancing people’s visual responses.

There’s also some early indications that the antioxidant qualities of cannabis may lead to reduced incidents of poor eyesight as people age, and research is ongoing to determine its exact role in helping protect people’s eyes.

How to Heal the Irritation

Everyone can experience different levels of eye redness when THC enters your body, or even none at all. One of the best ways to reduce the red and irritation that can be a side effect of THC’s ability to lower blood pressure is to utilize eye drops that contain tetryzoline, which causes your blood vessels to constrict. There are also natural substances that can reduce the redness, such as caffeine and licorice. If you do experience high blood pressure, it’s best to check with your doctor before eating or drinking items that may aggravate your condition.

Best Strains to Minimize Red-Eye

When considering your cannabis strain options, it’s important to note that people who experience high blood pressure aren’t as effected by red-eye as those with moderate to low pressure. This is because THC only lowers blood pressure in increments. So if you’re interested in using cannabis to help treat your glaucoma or other issues associated with high blood pressure, it’s good to choose strains with moderate to high levels of THC. For instance, one of the top-rated strains on our App that people use for treating their eye pressure contains 20% THC.

For those with average to low blood pressure who are interested in reducing eye redness, it’s helpful to find strains that are lower in THC. There are also certain cannabinoids found in cannabis which help offset the effects of THC. One of the most effective of these is CBD, which is why strains with higher levels of CBD are also great for keeping your eyes clear. You can learn more by exploring our growing list of community forums to find out how others enjoy cannabis’ many benefits and still keep the red away!