By Luke Sumpter

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.

External Resources:
  1. The Effect of Delta‐9‐Tetrahydrocannabinol and Cannabidiol on Blood Flow and Blood Pressure
  2. MARIJUANA AND GLAUCOMA - Marijuana as Medicine? - NCBI Bookshelf
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

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