A common side effect of cannabis use is red eyes (where the surface of the eyes turn red and blood vessels are noticeable). For many people, every time they use cannabis, their experience bloodshot eyes. What’s worse is that nobody assumes you might have an eye condition either, they just tell you that it’s dead giveaways that someone has smoked marijuana. However, others don’t seem to struggle with this as much. Why is that? And what causes this cliched “stoned” appearance?

Red eyes are not harmful, and you won’t have any long-term effects because of them. In fact, for many people who use medical marijuana the primary cause of red eyes is the reason they take cannabis medications.

DISCLAIMER: Eye health is extremely important, if you think your eye irritation goes beyond your cannabis use it’s best to consult an eye doctor or ophthalmology specialist. Certain eye infections could result in permanent vision loss and without proper medical advice you could be unaware your eye symptoms are the sign of something over-the-counter eye drops just can’t help. If you are feeling eye pain this is an especially concerning sign and you should probably book an appointment with your doctor or an ophthalmologist (eye specialist) as soon as possible.

What Causes Red Eyes?

There are several factors that can cause your eyes to appear red or bloodshot after you use marijuana. The main reasons red eyes occur are:

• Lowered Blood Pressure: One of the reasons medical marijuana is a useful treatment is because of THC’s ability to lower blood pressure. It’s especially beneficial as a glaucoma medication, as the condition is caused by increased intraocular pressure (the fluid pressure inside the eye). When blood pressure is lowered, it causes the vessels and capillaries to dilate. This increased blood flow causes eyes to appear red.

•  Smoke Irritation: Some eyes are just sensitive to smoke — it doesn’t matter if it is cannabis, tobacco or a campfire, their eyes will get red and irritated.

• Allergies: If you have an allergy to marijuana or smoke, using this plant or smoking it will more than likely make your eyes red. However, allergies to weed are very rare but are becoming more common as more people feel safe going to their eye doctor or allergist in places where cannabis is legal.

How do you get rid of red eyes fast?

Eye-drops

Speaking from personal experience I can tell you eyed drops (aka artificial tears) when done correctly work the best for red and irritated eyes. Furthermore depending on the brand you use you can quickly mitigate this telltale symptom of having just smoked a joint out back with your friends. If you need to know how to get rid of red eyes here are some great over-the-counter brands that offer a range of products made to best suit your specific needs. Let’s check them out!

Best Overall:

LUMIFY Redness Reliever Eye Drops ($12-$25): LUMIFY is a redness remover like no other. Before LUMIFY, redness relievers pretty much used the same ingredients for decades, and they had certain negative side effects that held people back from using them often. But then there was a break-through: eye doctors figured out that low-dose brimonidine tartrate could help relieve redness with a lower risk of certain side effects when used as directed.

Low-dose brimonidine restricts the venules, which helps to relieve redness without limiting the flow of oxygen. The results? Whiter, brighter looking eyes that last up to 8 hours - with a low risk of rebound redness when used as directed.

Best Budget:

Visine Redness Relief Eye Drops ($5-$9): When you just need quick, fleeting relief from red eyes, you can’t beat the original “get the red out!” brand: Visine. Visine’s redness relieving drops work right away for a multitude of red-eye causing reasons, whether it’s cannabis use, screen overuse, fatigue, or exposure to allergens. You can use them up to four times per day, but make sure you only do it for one or two days at a time—these can cause the dreaded rebound effect.

However, it’s worth noting that while most eye drops containing a vasoconstrictor rely on Naphazoline HCl, Visine uses a different decongestant, Tetrahydrozoline HCl. They’re both vasoconstrictors, but if you have an allergy to Naphazoline or some other reason for wanting to avoid it, you might appreciate that Visine offers an alternative.

Best for Dry Eyes:

Rohto DryAid Eye Drops ($15-$17): Eye doctors generally agree that getting to the root cause of your redness is the best course of action, so if your redness is thanks to excessively dry eyes, it’s smart to treat that problem first. With their unique Liquid shield technology, the advanced anti-dryness formula by Rohto targets three layers of your tear film to enhance your eye’s moisture levels.

What we like about these drops for dry eyes, is that they’re only designed to hydrate and moisturize. That means there are no risks for rebound hyperemia, and you may not need to reapply them much to solve your red eye problem since dryness is one of the biggest causes of red eyes in the first place.

Best for Contact Lenses:

Clear Eyes Multi-Action Relief Eye Drops ($11-$13): Sure, contact lenses are a great technological advance that allows people with less-than-perfect eyesight to go eyeglass-free but they can also be a real pain to care for, clean, and actually wear, especially if your eyes tend to be dry or sensitive.

“Patients should avoid red eye drops if they are wearing contact lenses,” advises Dr. Klinger optometrist at Clarkson Eyecare in St. Louis, Missouri. “The contact will absorb the medication and preservatives which can cause redness, irritation and can even dilate the pupil; patients can have blurry vision and become sensitive to lights when this occurs.”

So what should you do for red eyes if you wear contacts? Focus on keeping your eyes lubricated with something like the multi-action relief drops by Clear Eyes. Along with rewetting and removing irritating particles, these lubricating drops are specifically formulated to be used while you’re wearing your contacts. And because they don’t contain any pharmaceutical ingredients, they won’t harm your lenses, either.

Best for Itchy Eyes:

Bausch & Lomb Opcon-A Allergy Eye Drops ($8-$10): Sometimes your eyes are itchy because of seasonal or environmental allergens, but other times dryness or contact irritation from new makeup or shampoo products can be the culprit.

Whatever the cause, if your itchy eyes are also red and irritated, you need a product with a redness reliever and an antihistamine. The allergy eye drops by Opcon-A contain both, in concentrations high enough to fight back against the worst itching and redness around. They can tackle allergens of all shapes and sizes and can be used up to four times per day. 

The downsides? They do contain a decongestant, so use them sparingly, and their shorter stretches of relief can make it a pain if you wear contacts that need to be removed every time you want to re-apply the drops.

Best for Allergies:

ALCON Zaditor Antihistamine Eye Drops ($13-$23): How do you know if allergies are to blame for your itchy eyes and not something else, like pink eye or a wayward irritant? 

With allergic conjunctivitis, both of your eyes will usually be red and irritated in response to an allergen, while an infection tends to be associated with eyelash crusting, mucus production, and possibly swelling around the eye (only in one eye in some cases).

So once you’ve narrowed it down to allergies, the next step is figuring out how to treat them. Ongoing eye allergies should not be treated with an eye drop containing an ingredient that causes vasoconstriction (though you can take this route if you’ve had a one-off allergen exposure, like encountering pet dander or riding in a car with a smoker of cannabis or tobacco). 

For daily relief, though, Zaditor Antihistamine Eye Drops are a powerful way to combat all the itching you’re doing that’s giving you red-eye. Because there’s no risk of rebound, you can rely on these drops—which contain the antihistamine ketotifen—daily for allergic eye relief and say goodbye to your red eyes in the process.

Best for Watery Eyes:

Clear Eyes Complete 7 Symptom Relief Eye Drops ($7-$18): Despite how often allergies and irritation can cause your eyes to water, there actually aren’t that many eye drops that target watery eyes as a specific symptom. (Maybe it’s because dryness is often behind irritation, and that means you need more hydration, not less.)

Either way, if you’re tired of looking like you’ve been crying all day thanks to redness and overwatering, the Clear Eyes Complete 7 Symptom Relief drops can take care of both those problems for you (as well as grittiness, burning, and dryness). With a vasoconstrictor and three other ingredients designed to soothe irritation and restore the balance of your natural tears, you can rest assured that these drops will get your eyes looking normal again in no time.

Last Resort: Sunglasses

Wearing sunglasses whenever you’re out could already be a normal habit for you. They block the sun out of your eyes, they make it easy to people watch without being caught, and nobody can see that my eyes are as red as cherries! Although my sunglasses protect my eyes fairly well outside, that's the problem with sunglasses: they're no good inside, and they're no good at night (unless you’re trying to live out a particular 80s hit). This makes sunglasses the best choice for pretty much any outing that is outside and during the day! Besides, it's not like you will need to keep them on forever, just until your eyes return to their natural whiteness.

What is a Natural Remedy for red eyes?

Home Remedies

Other items you might have lying around the house can also trigger vasoconstriction. For instance, stimulants such as caffeine can help induce vasoconstriction. Therefore, drinking a fresh cup of coffee or enjoying a few squares of dark chocolate might help alleviate red eyes.

Cold water is also a strong vasoconstrictor. It forces the body to send blood toward our core to protect vital organs as part of a survival instinct. Splashing cold water on your face or placing an ice pack, cold compress, or a cool wet washcloth across your eyes can achieve this effect. If you’re brave enough, a cold shower or ice bath will also do the trick.

How long does it take for red eyes to heal?

Eventually, the redness caused by cannabis will eventually subside and return to normal. Therefore, you can be patient and simply wait for THC to run through your system. The key question is, however, how long do your eyes stay red after smoking marijuana?

Unfortunately, the answer isn’t clear-cut. You may have to wait from 2 to 12 hours, depending on a variety of factors, including the administration route and the dose of THC. For instance, when marijuana is smoked or vaporized, THC is rapidly absorbed into the bloodstream. Effects are felt within 2-5 minutes, peak within 15 to 30 minutes, and usually subside within one to three hours, depending on the dose.

Edible THC, on the other hand, is much slower and longer-lasting. It takes effect within 30 to 90 minutes, reaches maximum effect after two to three hours, and can last for four to 12 hours, depending on the dose! Individual factors, including your tolerance, body weight, and metabolism, also impact the pharmacokinetics (the fate of substances administered to a living organism) of marijuana and will determine how long it will take for your eyes to return to normal.

Of course, you only need to hide your red eyes if you want to. Many stoners choose to hide their red eyes only because of the stigma that follows them, or they don’t want to get caught by their boss when they are high on the job. There are some people who don't really care whether or not others know if they're stoned, so they strut down the sidewalk with their scarlet eyes. There's no crime of having some redness, and besides, you can always say you "just have allergies" if you need to. If you're in a state where cannabis is recreationally legal, you don't even need to do that!