Why Does Weed Cause Red Eye?

Some marijuana users hide the fact they are high better than others. In general, experienced users with a strong THC tolerance can function even while semi-intoxicated. However, a significant number of people have red eyes after using cannabis.

Even if you are not high, it is a clear sign that you have imbibed. It isn’t necessarily a problem if you’re at home with no intention of going anywhere. However, it becomes an issue if you have to work or socialize.

If you suffer from red eyes after taking cannabis, there are ways to prevent or treat it. We explore them later in the article. First of all, however, let’s discover how you get red eyes in the first place.

Cannabis, Red Eyes, and Changes in Pressure

One common misconception is that red eyes occur because the eyes rotate and bulge wildly when someone is high. In reality, it happens for the very reason that weed is so popular amongst glaucoma patients.

THC, the most prevalent and famous intoxicating compound in marijuana, typically elevates heart rate. In healthy individuals, it could also decrease blood pressure. As this happens, the blood vessels and capillaries dilate. These include the ocular (eye) capillaries. When they dilate, individuals experience an increased rate of blood flow to the eyes. This process can cause the eyes to turn red.

The blood pressure reduction also decreases intraocular pressure (IOP), explaining cannabis’ benefits for glaucoma.

The blood pressure reduction also decreases intraocular pressure (IOP), explaining cannabis’ benefits for glaucoma. Individuals who suffer from the condition have excessive pressure on their optic nerves. The positive link between marijuana and its short-term effects on glaucoma was first discovered in the 1970s. If left untreated, glaucoma could result in blindness.

Marijuana is potentially useful in lowering IOP. However, it is only effective for a very short time. Individuals using it for glaucoma need to consume cannabis 6-8 times a day for best results.

If you’re susceptible to red-eye after using marijuana, you’ll probably notice a greater intensity in color when you smoke a high THC strain instead of a low THC one. The change in pressure explains why you can get red-eye from edibles. The smoke doesn’t make your eyes red; the cannabinoids do.

What About Allergies?

It was originally assumed that the smoke from cannabis was responsible for red eyes. However, some people are allergic to marijuana, and red eyes are one of the symptoms.

Some cigarette smokers also experience red eyes from time to time. This is unsurprising since the human eye does not like having smoke in it. However, this theory does not explain why people experience red-eye after consuming marijuana via edibles, balms, oils, or tinctures.

Are There Any Contributory Factors?

Aside from allergies, there isn’t anything that specifically causes red eyes from marijuana use, barring the cannabinoids themselves. However, certain factors could exacerbate the effects:



Our genes have an impact on everything we do. Therefore, your DNA may mean a bad dose of red-eye from weed is inevitable.

Type of Strain:

Every marijuana strain contains a huge array of chemical and organic components. They interact with one another and with metabolic processes. Therefore, it is entirely possible to suffer from red eyes after using one strain but not after using another.


Novice users are the most likely to suffer from red eyes. Over time, you may show a greater level of resistance.


If you aren’t well hydrated, red eyes are more likely to occur. A prime example is if you get high and drink alcohol.

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How to Fight Back Against Red Eyes

One positive is that red-eye from cannabis use doesn’t tend to last more than a couple of hours. Therefore, you can always wait before deciding to leave the house. If this isn’t an option; there are a few things you can do:

Choose a Lower THC Strain

Pick a strain that is low in THC and high in CBD (and CBN) to reduce the chances of getting red eyes.

Invest in Eye Drops

Visine is a product that constricts blood vessels. It can alleviate your red-eye in a matter of minutes. However, please note that overuse of these products may cause more harm than good – so use sparingly.

Use Other Vasoconstrictors

Vasoconstriction is the constriction of blood vessels, which in turn increases blood pressure. This is the ideal way to counteract the blood pressure reduction properties of marijuana. It is also the reason why eye drops are a good choice. Other vasoconstrictors include cola, chocolate, and coffee.

Cold Compress

There are a few options for using cold compresses for red eyes. You can place cold cucumber slices on both eyes for around 15 minutes. Alternatively, you can put two green tea bags in the fridge after making tea. Take them out and place them on your eyes for 15 minutes or so to relieve the redness. Also, if you’re in a hurry, try an ice-pack across your eyes for 5 minutes. The last resort is to splash cold water on your face.

Final Thoughts on Marijuana and Red-Eye

The main issue with marijuana red-eye is the associated stigma. As a result, the condition can put people off the plant, which is a great shame. It is a clear sign that you’ve been using cannabis. However, red-eye is completely harmless and only lasts a short time.

Experiment with different strains and gradually reduce the THC content if you suffer from extreme red-eye.

You should experiment with different strains and gradually reduce the THC content if you suffer from extreme red-eye. When you consume cannabis, do it in a well-ventilated area and stay hydrated. Also, don’t mix marijuana and alcohol!

Consider investing in some Visine if you plan on smoking before leaving the house. It has been a staple of marijuana advocates for over half a century and is often a real lifesaver!

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