It’s hard to get away with a great high when your eyes are hazy, puffy and bloodshot. Eye drops may protect you a bit. Sunglasses and tinted contacts might help. But it sure is annoying.

So why do your eyes go red when you smoke weed? Is there a scientific explanation? And what can you do to keep your peepers clear, white and innocent-looking?

Weed is not the only intoxicating drug that causes red eyes. Too much alcohol, too much cocaine, almost any amount of methamphetamine will turn your eyes bloodshot. But it all depends on the person.

Some people are simply more sensitive to red eyes, and there’s not an awful lot that can be done to change that. Most potheads will have the experience at least once, but it’s far more common for some users than others. If your eyes tend toward the bloody, you’ll just have to work harder at covering up.


Why does cannabis make your eyes red?

THC, the primary psychoactive chemical in marijuana, lowers blood pressure. This then causes blood vessels in the eyes to expand, or dilate. As the ocular capillaries dilate, blood flow increases and pressure inside the eyes drops. The extra blood flow gives the expanded capillaries their bloodshot look, creating a web of red within the whites of the eyes.

This is why cannabis is widely used to treat glaucoma, a serious chronic eye disease that causes high pressure within the eyes, leading to permanent vision loss and severe pain. Pot reduces ocular pressure and staves off glaucoma’s worst complications.

Why does weed give you red eyes

It’s important to note that red eye is not caused by marijuana smoke. Instead, it’s triggered by THC and other chemicals in the pot plant known as cannabinoids.

The dose of cannabinoids delivered by the weed you smoke helps determine how red your eyes become (as do your genes, allergies and general sensitivity to marijuana). Smoking a bong-load of low-grade cannabis one day may have no effect while a few puffs of high-grade pot the next could leave you scrambling for Visine.

How to avoid or get rid of red eyes? Here are a few tips.

1. First, pick strains that deliver less THC. Many strains are high in CBD and other medically beneficial cannabinoids but low in THC. This means you won’t get as high, but if you’re more concerned with medication than recreation, this is a good way to keep your eyes white.


2. Always have eye drops handy. The best brands are specially formulated to treat redness. And drink lots of water. Red eyes often come with dryness, and extra hydration makes that less likely.

Visine is usually the brand of choice for panicked stoners. It’s easy to find at any 24-hour drug store, it’s cheap, and holding it isn’t probable cause. Visine is a decongestant, and it works by constricting the blood vessels in the eye, much as it would if you had a cold.

But don’t overdo it. Using Visine or any decongestant on your eyes for more than two or three days can make the problem worse. And Visine can trigger allergies or interact badly with certain other medications.

Alternatively, use artificial tears. Though these don’t constrict the blood vessels, they will reduce irritation and dryness. And they’re safer and less irritating than Visine.

Or, what the hell, just roll with it. Go to the bank and make a suspiciously large withdrawal or deposit. Flag down a cop for directions. Visit your local dispensary and ask if they know where you can score some PCP. You know, have fun with it.

Because once that dreaded red-eye appears, you’re going to have a heck of a time convincing anyone you’re sober.

What do you think: Are red eyes a serious problem for you? Do you even care if people see you with bloodshot eyes?


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