Why Do Your Eyes Get Red When You Smoke Weed?

Why do your eyes get red when you smoke weed? man with red, bloodshot eyes

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Red eyes: they are known to represent allergies, exhaustion, overnight flights, and stoners. So, why do your eyes get red when you smoke weed?

When it comes to marijuana, red eyes are a surefire indicator of recent activity; accepted as a dead giveaway, if you get caught with a reddish tint, you can go ahead and label yourself as #busted.

However, even with its status as a dead giveaway for weed smokers, there is some science involved too. Like everything to do with cannabis, our bodies react on a biological level to the herb. Everything from a high to scientific relief has a scientific reason behind it, including red, hazy eyes.

There's even variation between users; some people's eyes turn red every time they smoke, some people experience different levels of redness based on potency, quality, or quantity of marijuana consumed. There can even be discrepancies between people that smoke and those that eat an infused edible, though no two cases are exactly the same.

Pressure Change

The top reason that eyes turn a reddish hue after smoking a bowl comes down to pressure change. Simply put, weed makes alterations within the eyes' blood vessels. This change in pressure affects the body in different ways before reaching the eyes, which can be broken down into simple steps:

  1. THC, the main psychoactive cannabinoid in weed, lowers blood pressure when it gets in your body's system.
  2. When blood pressure is lowered, blood vessels and capillaries dilate or expand.
  3. The white area of the eye, known as the sclera or inner eye, contains a lot of small blood vessels. Usually, these blood vessels go unnoticed, unless they become enlarged.
  4. Ocular capillaries within the sclera or inner eye dilate and expand due to low pressure.
  5. Dilated ocular capillaries lead to an increase in blood flow to the eyes, and gives small blood vessels more room to expand. Since the sclera is normally white, the redness of the blood vessels stands out and draws attention to their new blood-shot look.

Overall, the increased blood flow and lack of pressure create the redness in the eyes after smoking weed. This reaction is nothing to be worried about, and should not be a cause for alarm. In fact, red eyes are a sign that the cannabis is working.

Eye Irritation

Urban legends have linked eye redness and weed to eye irritation. It does seem logical, since our eyes can become tinted when we come across other irritants, such as allergens or smoke.

And while some people might have red eyes due to smoke irritation (while possible to have an allergic reaction to cannabis, it is a small percentage of consumers), this is not a major factor. Red eyes are a mostly internal reaction and have little to do with allergies, sinuses, and eye sensitivity. This is supported by the diversity of red eyes and weed: consumers can still get red eyes after eating an edible. It’s suggested that cannabinoids (namely THC) are the leading cause of redness, not the smoke. You can figure out if you have a sensitivity to smoke if you have the same reaction across the board, from tobacco, weed, and incense smoke.


Coping with Red Eyes

Luckily, red eyes won't last forever. And yes, while they are not an indication of something going terribly wrong, red eyes from smoking weed are inconvenient and sometimes a built-in tattle tale—something many consumers do not want. There are a few ways to cope with red eyes:

  • Use eye drops. Eye drops are a handy tool in soothing the eyes and eliminating redness, used in moderation. Many stoner veterans reach for Visine, which has a reputation for helping constrict blood vessels and getting the eyes back to pearly white.
  • Turn to a cold compress. Pressing a cold, damp towel on your eyes can help to soothe irritation.
  • Wait it out. Whether this involves hiding in the comfort of your home or covering your eyes with a pair of tinted sunglasses, waiting out the red storm is one method of keeping your eye color to yourself. Your eyes should return back to normal after a few hours, so be patient.

Next time you find yourself getting read eyes when you smoke weed, don't panic: there's nothing to be worried about.