what causes red eyes when smoking weed

Why Cannabis Causes Red Eyes

Red eyes are the most obvious giveaway that someone has just polished off a fat joint. Although no big deal when you’re in the right setting, red eyes can give you away when you’re trying to be low-key about your passion for weed. Use the tips mentioned below to reduce eye redness after a joint, and learn how to prevent it in the first place.


After consuming cannabis, herb-lovers exhibit several signs that make it obvious they’ve indulged. Aside from intermittent giggling, a dopey smile, and a raging appetite, red eyes are one of the most obvious clues that someone has inhaled THC.

Having eyes as red as roses while sitting around with your smoking buddies is no big deal. However, strolling into work or public settings with bright red eyes can easily give the game away. Therefore, smokers should be familiar with a few strategies to conceal their altered state of consciousness. Continue reading to find out why weed makes your eyes red in the first place, how to get rid of red eyes, and how to prevent them from occurring to begin with.

What Causes Red or Bloodshot Eyes?

Of course, your eyes can turn red for reasons other than inhaling cannabis. Several associated symptoms can arise when the eyes turn red and you’re stone sober, including soreness, itchiness, watery eyes, and twitching. These symptoms are often caused by conditions such as:

  • Dry eyes
  • Conjunctivitis
  • Burst blood vessels
  • Blepharitis
  • Ingrown eyelash
  • Eyelid problems

The eyes can also become bloodshot for other reasons, such as drinking too much booze, staying awake all night, and reading in poor light conditions. The term “bloodshot” simply refers to the reddening of the whites of the eyes due to irritation or rupturing of the blood vessels.

However, none of these mechanisms explain why cannabis specifically makes the eyes red.

Why Does Cannabis Cause Red Eyes?

Cannabis causes the eyes to turn red for two primary reasons. One mechanism involves systemic changes, and the other involves external irritation.

Cannabis Lowers Blood Pressure

Cannabis strains containing moderate to high levels of THC appear to cause a slight drop in blood pressure [1] . This shift prompts the blood vessels and capillaries to dilate, in turn causing them to widen and allow more blood to pass through. After smoking weed, the small blood vessels in the eyes widen and deliver more blood into the eyes, making them appear red.

This mechanism also underpins the potential positive effects of cannabis [2] on conditions such as glaucoma—a pathology characterised by high levels of pressure within the eye. The vasodilation that occurs after smoking weed appears to reduce pressure within the eye.

Smoke Can Irritate the Eyes

Cannabis can also redden the eyes via irritation. Every smoker has experienced the misfortune of taking a plume of smoke to the eye at some point. This unpleasant sensation causes stinging and watering; however, this type of reddening usually clears up within a few minutes. In contrast, the other form of redness only resolves after the effects of THC begin to wear off.

How to Get Rid of Red Eyes

There are numerous strategies cannabis users can employ to reduce eye redness. Whether you’re on the way to a family gathering or couldn’t resist firing up a joint on your lunch break, use the tips below to conceal your high.

Eye Drops

In the modern era of cannabis, companies have developed products specifically to remedy the issue of red, bloodshot eyes. Cooling eye drops help to reverse the mechanism that underpins red eyes in the first place, and they do so very quickly. Apply drops according to the product instructions to return your eyes closer to their normal state.

Stay Hydrated

Keeping yourself topped up with water will help alleviate any dryness that accompanies your red eyes, possibly taking the edge off their newfound colour.

Throw on Some Sunglasses

If the two previous methods aren’t working, slap on some sunglasses as a last resort. Of course, how out-of-place this appears will vary greatly depending on the location and situation. If you’re meeting family for lunch under the Cali sun, you’ll get away with it. If you live under the grey skies of the UK and are catching up with your gran for dinner, you might look even more suspicious wearing them.

How to Prevent Red Eyes From Cannabis

Treating red eyes does work in some cases, but sometimes the stoned glow just can’t be contained. If you experience particularly extreme red eyes, you’ll want to focus on preventing the look as opposed to treating it. Use the tips below to avoid red eyes in the first place.

Smoke Low-THC Strains

If you’re in the mood for a smoke but have somewhere to be, consider smoking low-THC weed. Cannabis low in THC and high in CBD still offers an enjoyable and clear-headed effect, just without the glaring red eyes.

Eat, Vape, or Drink Your Cannabis

There are plenty of different ways to consume weed. Choosing an option that doesn’t carry the risk of introducing smoke into your eyes will help you avoid excessive redness caused by this irritating phenomenon. Do note, however, that these other forms will still cause red eyes due to systemic changes.

Are Red Eyes Dangerous?

No. The mechanism that underpins red eyes won’t hurt you. In fact, it might help you if you experience intraocular pressure. However, red eyes might get you into trouble in a different way. If you can’t risk getting caught high, red eyes can land you in a situation you’d rather not be in. Use the tips mentioned above to manage red eyes while enjoying cannabis whenever you so choose.

Ever wondered why your eyes appear red after smoking weed? Discover the science that underpins this phenomenon, and learn how to treat and prevent it.

Why cannabis makes our eyes red and how to get rid of it

The infamous red eyes syndrome, and what you can do to prevent this side effect of marijuana

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    Before we get into the specifics of the red-eye syndrome, I just want to say that the redness of the sclera (also known as the white of the eye) is a completely non-dangerous side effect of cannabis consumption, so if you’ve found this article to check if you’re in any immediate danger, do not fret, everything is quite alright.

    On the other hand, if you want to get all the facts about red-eye stay tuned, as we’re going to cover all there is to know about this classic pot-lover giveaway.

    Why cannabis makes our eyes red and how to get rid of it Back to video

    Why do your eyes get red when you’re high?

    Even though many people still believe that red eyes are caused by the smoke from a joint (or a blunt or a bong), this is completely untrue, because no matter what type of consumption a person chooses, ranging from smoking, edibles, dabbing or vaping, your eyes will turn red. The reason behind the redness is actually THC.

    One of the many ways tetrahydrocannabinol affects us is by decreasing our blood pressure. One of the effects of decreased blood pressure is the expansion of our blood vessels (which include arteries, veins, and capillaries). In the case of our eyes, the ocular capillaries become dilated and take in more blood, and the expanded blood vessels on the surface of the sclera make eyes appear redder.


    Article content continued

    Tetrahydrocannabinol (by reducing blood pressure), also reduces the intraocular pressure of the eye. Increased intraocular pressure is the key factor for all glaucoma diseases, and lowering the IOP (or intraocular pressure), is the only way for us to battle glaucoma, which when left untreated can result in a severe loss of vision, and ultimately blindness. One of the first studies conducted on this correlation showed that high THC strains can lower the IOP in the range of 25% to 30%.

    The main issue with treating glaucoma with marijuana is that the IOP needs to be constantly lowered in order for the eye to function properly (edibles are best for this because of their extended duration), while the second issue is that the users who constantly consume large quantities of THC can experience some side effects in their everyday life.

    Bloodshot volume: It varies from person to person

    If you and the people around you regularly consume cannabis, you probably already noticed that the same strain has different effects on different people. These differing effects happen due to a number of key factors which include genetics, sex, overall health and frequency of consumption (increased frequency causes cannabinoid tolerance). You also might have noticed the same thing about the eyes. Some people get really intense bloodshot eyes, while on others the difference is barely visible, or even non-existent.

    The redness is completely dependant on the person’s blood pressure. For instance, if you have high blood pressure, THC won’t be able to decrease it enough for your eyes to become really super-red. I myself actually have a completely opposite problem, as my blood pressure is rather low, so when I consume a potent THC strain, I literally look like the Terminator.


    Article content continued

    Besides the redness, when the session includes several joints/blunts I can also experience weakness in the legs and symptoms like feeling faint. This, of course, isn’t only a result of a low blood pressure but is brought about from a complex equation of factors I previously mentioned like age, sex, health, genetics etc.

    Allergies can also play a factor in the overall “bloodshot volume”, as there are many people who are very sensitive to smoke in general. Another possibility for increased redness is cannabis allergy, but for users who have this unfortunate issue, red eyes are the least of their concerns.

    How to get rid of red eyes after smoking weed

    The most common way to alleviate your red eyes is, of course, through various over-the-counter eye drops that are designed for eye allergies, redness and itchiness. Pretty much all variations contain tetryzoline (also known as tetrahydrozoline), which is an alpha agonist that causes dilated blood vessels to constrict. As previously mentioned, THC makes our blood vessels and capillaries to dilate (directly causing the redness), so the eye drops reverse this effect and return our eyes to a normal state.

    These types of medications are generally quite safe for use, but I strongly recommend that you always carefully read the manual that comes with the drops. There are a few alternatives to eye drops which can also constrict the blood vessels in our body, such as caffeine, chocolate, liquorice, and sodium.


    Article content continued

    A common misconception is that increased hydration can be used for reducing the redness of the eyes, which is unfortunately entirely false. People frequently perceive the redness as a sign of dehydration, because they associate it with the accompanying sensation of dry mouth.

    One of the many ways cannabis influences us is by activating the endocannabinoid receptors that are found in our salivary glands. Once excited by cannabinoids from weed, they slow down the fabrication of saliva, which causes us to feel like there’s a desert where our mouth used to be. is an educational website dedicated to shedding the light on many unexplored sides of medical and recreational cannabis. Aside from informing people of safe cannabis use, Greencamp also provides technology for finding optimal cannabis treatment.

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    When you consume or smoke marijuana products, high eyes or red eyes are a common side effect. Don’t worry, we have the remedy.