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Why Does weed make your eyes red

Why Does Weed Make Your Eyes Red and How to Manage It?

One of the side-effects of smoking weed is the reddening of the eyes.

Sometimes referred to as ‘high eyes’, it is a common byproduct of smoking marijuana that is normal and temporary.

The primary reason for getting red eyes after smoking pot is THC- the main psychoactive compound found in cannabis.

It is the ratio of the THC consumed that decides the intensity of reddening and its duration.

The lower the THC, the lesser the redness.

Why Weed Makes Your Eyes Red?

Weed is known to stimulate many bodily functions including sleep, appetite, mood, and so on.

But the first thing it does is increase our blood pressure and heart rate. 

This sudden pump in the metabolism is caused by a variety of chemical compounds and cannabinoids such as CBD, THC, CBN, and terpenes that are present in weed in different amounts.

Each compound has its properties and effects. For example, THC or tetrahydrocannabinol is the main psychoactive compound found in cannabis, that is responsible for the infamous ‘high.’ Yet, that’s not the only thing it does. 

As a natural cannabinoid, THC can connect and interact with our endocannabinoid system (ECS) which regulates many of our biological functions.  Among them is, the flow of ions in and out of a cell through what’s known as ion channels.

These ion channels are what control the contraction and relaxation of the muscle cells, and hence the size of the blood vessels in the eyes.

The interesting thing is, that most of these cannabinoids are naturally secreted by our bodies in required amounts. It is only when we pump more of them into our system that we start experiencing a hype in our blood pressure and heart rate, much like when we exercise or get into physical labor. So, it’s perfectly normal.

Now, as the blood pressure slows down after a while, it also forces our blood vessels within the eye aka ocular capillaries to dilate or expand in a process called vasodilation.

This increases the blood flow to the eyes, in particular, the white part and under the eyelids, eventually turning them red and reducing the intraocular pressure.

It is for this reason, that patients suffering from glaucoma or partial blindness are sometimes prescribed marijuana.

Nevertheless, being an individualistic experience, the effects of smoking pot varies from person to person.

Some people may experience more redness than others which largely depends on individual factors such as genes, sensitivity, and tolerance power.

In general, though, it all depends on THC levels.

For instance, a person with lower or lack of THC content in their cannabis products and treats might experience little to no puffy eyes at all. Whereas, someone who has consumed a higher THC concentrate might end up with distinct-looking bloodshot eyes.

At the same time, the level of movement, activity, diet, mental state, and health conditions could also affect the overall impact of smoking marijuana.

In any case, if being caught with red eyes isn’t your ideal date, then choosing a low-THC strain might be the wisest idea. Coz higher THC strains and products will only produce more long-lasting effects including the reddening of the eyes.

Those buying weed from a legalized weed dispensary should have that very easy given the descriptive labeling with clear ratios of different ingredients and the overall strength. But those who still depend on a black market peddler, well, beware!

The Science Behind Red Eyes

Red eyes are a common physiological effect of smoking marijuana, in particular THC. But it’s not limited to smoking only. 

That is, since THC is the main culprit behind red eyes, any cannabis product that has it can cause it regardless of the method of consumption.

Be it through smoking, vaping, eating, or drinking, if there is THC in your weed products, chances are you might end up with red or dry eyes even if it is only for a few hours.

As I said earlier, THC is one of the main cannabinoids in cannabis with a tendency to bind and stick to our endocannabinoid receptors. While interacting with our ECS, it makes several physiological changes and mind-altering effects, even if only temporary.

By lowering our blood pressure, it first dilates the blood vessels and then increases the blood flow throughout the body. This in turn causes the blood vessels in the eyes to expand making them appear crimson red.

As worrisome as it looks, THC does not have any permanent negative effects on the vision.

Instead, it is believed to have positive therapeutic benefits for those suffering from vision-related issues such as Glaucoma. Caused by a higher eye pressure aka ocular hypertension, Glaucoma can lead to serious concerns including a complete loss of sight.

This is where THC, which ultimately leads to reduced intraocular pressure, comes into the picture.

Although, not an FDA-approved drug yet, many people are using it nonetheless while researchers continue to examine the potential effects of marijuana on several eye-related issues such as high intraocular pressure (IOP), peripheral vision, visual processing, and so on.

Common Myths and Misconceptions

Myth: Allergic Reactions

One of the most common misconceptions about catching red eyes after smoking marijuana is that it is an allergic reaction, which is far from the truth.

While smoke from a marijuana cigarette can certainly irritate your eyes and turn them red for a while if it goes in; it’s similar to any other type of smoke like that of burning wood or cooking spices which can also lead to irritation and temporary redness in the eyes.

So, it is not an allergy but a momentary reaction.

Myth: Poor Quality Weed

Another myth associated with the reddening of eyes due to weed is that it is caused by only poor quality weed.

Again, the quality or age of weed does not make a lot of difference here as it is all about the quantity of THC intake.

The higher the THC, the more and longer the reddening will stay.

How to Manage Red Eyes from Weed

Although red eyes from weed is not at all a serious issue, it can certainly tell others that you are stoned.

To keep the ‘high’ to yourself and not in the eyes, there are many things that you can do. For instance-

  • Hydration

Drink ample water and fruit juices especially lemonade or lime juice as it is a natural weed detox.

Keeping yourself hydrated can also help you overcome dry eyes which is yet another symptom of smoking too much marijuana.

  • Cold Compresses

Using a clean and wet cloth is an age-old trick to reduce swelling and inflammation.

In the same way, applying a cold compress on red eyes can reverse the dilation of the blood vessels and thus reduce the redness all the while. 

  • Choosing Strains

Perhaps the most important measure that you can take to avoid getting red eyes from weed is to choose a low-THC or THC-free strain.

Those looking to gain its medicinal effects only might want to switch to CBD-rich products which is non-intoxicating and does not cause any ‘high’ or ‘high eyes.’

Additional Tips for Preventing and Reducing Red Eyes

  • Moderation and Dosage

Refrain from frequent use of cannabis and consume it responsibly with sufficient breaks in between your pot sessions.

By lowering your dosage, especially, that of THC, you can reduce the overall reddening effect of consuming weed.

Beginners might also want to start their cannabis journey with lower amounts of THC and even weed as a whole for that matter. Once comfortable, you can gradually increase the dosage to get the desired effects without catching excessive redness.

  • Environmental Factors

External factors such as the environment, quality of air, ventilation, etc. can also make an impact on the supposed effects of marijuana.

To be safe, stay away from polluted and industrial areas, avoid driving or operating heavy machinery while smoking, or mixing your weed with other intoxicating substances such as alcohol.

  • Healthy Lifestyle Choices

When it comes to using drugs, be it for fun or medicinal purposes, it is crucial to be extra conscious of your health and lifestyle.

To manage and overcome the unwanted effects of marijuana or any other drug for that matter, one should include consistent workouts, hygiene, and a healthy diet plan.


Reddening of the eyes is a common side-effect of weed. And it is not an allergy or symptom of a disease.

As a normal reaction, it is a temporary byproduct that occurs mainly due to THC.

So, while changing the method of consumption may not be the right step, changing the product from THC to CBD can make all the difference. 

If that’s not feasible should your only poison be THC, you can always follow the above tips for a safe and sound experience.


No, since CBD is a counterpart to THC, and does not leave any psychoactive effects, it does not cause the reddening of eyes.

High eyes or red eyes caused by smoking weed can last for anywhere between a few to several hours. If it does not go away even after 24 hours, make sure to get in touch with a professional eye specialist.

Not due to the weed but contact lenses themselves can lead to certain complications such as a scratch or infection.

Red eyes from weed are mostly temporary and do not make any impact on your vision or eyesight in the long term.

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