Skip to main content

When smoking cannabis, you’ve probably encountered the “red-eye syndrome”. It’s easy to tell when someone has been smoking cannabis because the white of the eye (sclera) turns red. Luckily for you, it’s completely harmless and doesn’t affect you in any way, other than being a quicker indicator to others that you smoke.

Want to find out how to help alleviate red eyes? We have gathered a few reasons why this happens and how you can get rid of it.

Why do your eyes turn red?

To start, many people assume that red eyes are caused by the smoke exhaled after smoking flower or a vape, but this is actually untrue. Although smoking obviously produces a lot of smoke that could get in your eyes, that’s not actually the reason for your red eyes. No matter how you take in cannabis, your eyes will still turn red.

The reason is actually that of the THC inside of cannabis. This is the compound that gives you the euphoric feeling you’ve come to expect when smoking, and one of the effects it has is decreasing your blood pressure. This ultimately leads to the expansion of our blood vessels to allow more blood to flow around our body. In the case of eyes, it means that our ocular capillaries are dilated so that they can take in more blood. These expanded blood vessels make the white of the eye appear red, hence the effect.

However, THC also reduces the intraocular pressure of the eye. Increased intraocular pressure is a key factor when it comes to glaucoma diseases. Lowering the intraocular pressure is actually the way we battle against glaucoma. If left untreated, it could lead to a severe loss of vision and also blindness. This is why THC strains can actually help to lower intraocular pressure anywhere between 25 to 30%.

The amount your eyes “turn” red will vary from person to person. If you smoke the same strain with someone else, you might notice that their eyes stay relatively white while yours can go extremely red, or vice versa. A number of factors can affect this, such as your genetics, sex, health and also how often you smoke. The redness is completely dependant on your blood pressure and it can last varying different timeframes as well.

Getting rid of red eyes

The most common way to get rid of bloodshot eyes after smoking is to use over-the-counter eye drops that are designed to overcome allergies. These contain tetryzoline which is an alpha agonist that causes dilated blood vessels to constrict. As previously mentioned, THC makes blood vessels and capillaries dilate, thus causing the redness. Eye drops can reverse this effect, returning your eyes to their normal whiteness and helping to relieve red eyes very quickly. This is a safe method to get rid of bloodshot eyes and it’s recommended that you read through the manual in order to get a good understanding of how to use them properly.

This is generally the best and fastest way to get rid of red eyes, but there are also other alternatives that can help constrict the blood vessels to reduce redness. This includes consuming chocolate, more sodium or even caffeine.

However, a misconception that you might hear is drinking more water to help you reduce redness in the eyes. This is sadly entirely false. Red eyes are not a sign of dehydration so no amount of water intake will help you get rid of bloodshot eyes.


The redness in your eyes isn’t anything serious, so you shouldn’t be alarmed. There’s nothing to be worried about and you’re generally not going to suffer any negative effects if do you have red eyes, but it can be worrying if you’re expected to attend a meeting or a work-related event.

So in short, get yourself some eye drops! They’re the fastest and easiest way to get rid of bloodshot eyes, and you’ll typically find them at the nearest pharmacy or convenience store!