Red eye from cannabis

Caught Red Eyed?

Similar to having the giggles or a serious case of the munchies, having a pair of red and bloodshot eyes is a key giveaway that you’ve recently been enjoying cannabis.

You may have heard that dry red eyes occur if your eyes find cannabis smoke to be an irritant. However, this would not explain why your eyes turn red after a dose of edibles or when using a Vaporizer.

You also may have noticed that red eyes doesn’t happen every time or that cannabis turns your eyes redder than your friends.

Have you ever wondered why this happens and it means? Read on to have your question answered!


So why does cannabis turn your eyes red?

Red Eyes are the result of Tetrahydrocannabinol better known as THC.

One of the effects THC has on the human body is that it lowers blood pressure - this is why some users experience a slightly increased heart rate after using cannabis; similar to the increase in heart rate during exercise or sex.

Low blood pressure encourages the dilation of our arteries, veins and capillaries so that they can carry the increased amount of blood being pumped around your body by your heart.

The sclera (white of the eyes) have tens of thousands of tiny capillaries and when these dilate they allow more blood to flow through the eyes. This gives the appearance of Red Eyes.


Are red eyes harmless?

Yes. In fact, it is for this very reason that doctors have begun prescribing cannabis to their patients. For example, a symptom of glaucoma and related diseases is suffering from an increase in the intraocular pressure in the eye.

Because it reduces the intraocular pressure of the eye, THC has become a key component in the battle against glaucoma.

Studies show that cannabis strains high in THC can lower the intraocular pressure in the eye between 25% - 30%.

Whilst it’s important to note that THC does not cure glaucoma; it does help sufferers lead normal and happier lives.


Why do red eyes affect me more than my friend?

Cannabis and Hemp plants are complex plants and made up of over 113 different cannabinoids. I’m sure you’ll have noticed that each strain affects different people in different ways. This is because of the way that cannabinoids effect you can depend on your gender, age, tolerance and overall health.

This is true for red eyes as well; some people may experience the most intense red and dry eyes whilst it may not affect others at all.

The ability of THC to turn one’s eyes red depends on their blood pressure. For example, I suffer from blood pressure that is slightly above the average. As a result, I’m rendered immune to red eyes unless I’m using dabs or concentrates with very high levels of THC.


How do I prevent Red Eyes?

Terminator has red eyes from vaping too much

- The Terminator probably needs to try a strain high in CBD

Just because red eyes are harmless it doesn’t mean they are welcome! Luckily, there are a few simple steps to help alleviate red eyes.

Eye drops, help to lubricate dry red eyes because they typically contain potassium and hydrochloride. These compounds encourage the eye to constrict its capillaries which lessen the redness of your eyes.

Also, you should consider using a strain of cannabis low in THC or even consider switching to CBD Herb or even CBD E-Liquid. Strains high in CBD tend to have less THC. CBD does not encourage low blood pressure which means no red eyes!

Finally, it always helps to stay hydrated. This is good advice whether you are using cannabis or not but if you are drinking plenty of water you are less likely to suffer from dry uncomfortable eyes!



  • Cannabis causes your eyes to appear red because the THC lowers blood pressure which in turn encourages your blood vessels to dilate.
  • Your eye contains tens our thousands of tiny blood vessels and when these are enlarged they give the appearance of red eyes.
  • If you want to avoid red eyes you should vape strains high in CBD or use eye drops to lessen the effect.