effects on marijuana red eye

Why does weed make your eyes red?

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  1. Under pressure: lower blood pressure and dilated capillaries
  2. Do edibles make your eyes red?
  3. The redder the better?

Among the most common effects of marijuana use (and telltale signs you’ve recently partaken) is red, bloodshot eyes. It’s to be expected, sure, but that doesn’t answer the mysterious question pondered by generations of stoners: why does weed make your eyes red?

For weed novices, the onset of bloodshot eyes could cause a panic-induced internet search asking “ can smoking weed damage your eyes? ” Thankfully, as those who regularly consume cannabis can tell new users, there are no serious health risks associated with your sudden red-eyed circumstance. You’re probably not experiencing an allergic reaction or some bigger complication. Some might poke fun or chastise you for sporting your so-called “ weed eyes ” in public, but otherwise, it’s a completely natural occurrence that transpires after smoking cannabis.

In fact, your eyes turning red has nothing to do with the act of smoking at all.

Under pressure: lower blood pressure and dilated capillaries

After consuming a cannabis-based product (flower, concentrate, edible, etc.), users generally experience an increase in heart rate and blood pressure. This effect is due to the plant’s cannabinoids, which are chemical compounds responsible for some of the therapeutic and medicinal benefits of cannabis, and their initial interaction with the body. This rise in blood pressure and heart rate is comparable to normal physical activities like exercise or sex.

It generally takes about five to ten minutes for users’ heart rates to return to normal and for blood pressure to begin to decrease. As the blood pressure lowers, the blood vessels and capillaries dilate, including the ocular capillaries . The dilation of ocular capillaries causes increased blood flow to the eyes, which results in your eyes turning red and also reduces intraocular pressure.

The dilation of ocular capillaries causes increased blood flow to the eyes, which results in your eyes turning red in the process, and also reduces intraocular pressure. Photo by: Gina Coleman/Weedmaps

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In fact, according to Dr. Melanie Bone, a board-certified OB-GYN who practices in West Palm Beach, Florida, “It’s cannabis’ ability to reduce intraocular pressure in the eyes that makes it a potentially viable treatment for glaucoma , a group of eye disorders that causes damage to the optic nerves which can eventually lead to blindness. It also happens to explain why your eyes become bloodshot after smoking cannabis.”

Evidence that the THC found in cannabis can lower intraocular pressure (IOP) is a major reason why many glaucoma patients have attempted to use medical marijuana to treat and relieve symptoms of the disease. It’s important to know that some studies have contradicted or added a caveat to the claim that cannabis is beneficial for glaucoma. For instance, a 2018 study conducted at Indiana University found that cannabidiol (CBD), the non-intoxicating cannabinoid found in marijuana, could potentially worsen the condition by increasing eye pressure . More research into the use of cannabis for glaucoma treatment is needed.

Do edibles make your eyes red?

Similar to smoking cannabis, ingesting edibles could also make your eyes turn red. Again, this depends on the amount of THC consumed. Remember, it’s not the smoke itself that makes your eyes red, but rather the ability that cannabinoids have to lower blood pressure, causing blood vessels and capillaries to dilate.

The redder the better?

The amount your blood pressure is lowered and how red your eyes become depends on the amount of THC you consume.

Tetrahydrocannabinol (THC), the most common cannabinoid in the plant, is responsible for the intoxication associated with smoking cannabis. The greater the concentration of THC in a cannabis product, the stronger the effects and the redder your eyes become.

The greater the concentration of THC in a cannabis product, the stronger the effects and the redder your eyes become.

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So, red eyes can act as a sign that your cannabis has a high cannabinoid content (i.e., it’s potent). In other words, if your eyes are noticeably bloodshot after consumption, there’s a good chance you’ve landed yourself some highly potent weed.

Other than being a dead giveaway that you’ve recently consumed cannabis, you have no reason to be concerned about the redness of your eyes. Cannabis-induced eye redness will typically only last a few hours and can easily resolve if you have the right tools at your disposal.

It isn’t a bad idea to have eye drops (or some sunglasses) on hand. Look for eye drop brands that are specifically designed to reduce eye redness. There are other methods that could potentially help combat cannabis-induced bloodshot eyes, including staying hydrated, washing your face and eyelids with cold water, or simply consuming cannabis products with lower THC levels.

Ever wonder why using marijuana or cannabis makes your eyes red or bloodshot? Discover why weed gives you bloodshot eyes.

Red Eyes

Updated on January 30, 2019. Medical content reviewed by Dr. Joseph Rosado, MD, M.B.A, Chief Medical Officer

A common side effect of marijuana use is red eyes. For many people, every time they use cannabis, their eyes appear to be bloodshot. This is considered one of the dead giveaways that someone has smoked pot. 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.

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. However, 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.
  • Allergy: 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.

Get Rid of Those Red Eyes

Unless you have an allergy to cannabis, the cause for red eyes is harmless. For some, it’s even beneficial. The best thing to do is just to let it fade away naturally. This isn’t a long-term side effect — it usually wears off after a few hours.

However, if you need to go out and about, you don’t necessarily want to leave the house with bloodshot eyes. Here are some tips on how you can minimize the appearance of red eyes:

  • Try a Different Strain: If the strain you use is high in THC, it doesn’t matter whether it’s a smokable or edible, it’s more likely to make your eyes red. Try strains high in CBD or CBN instead.
  • Switch Up Your Ingestion Method: If smoke irritates your eyes, try a different method of ingestion, like vaping or edibles.
  • Use Eyedrops: Using eye drops specifically designed to reduce eye redness can help. They constrict the vessels in the eye, thus causing them to appear less red. It’s a good idea to carry these around with you and use the drops multiple times a day. Don’t share your drops with others, as this can lead to eye infections.
  • Drink Lots of Fluids: If you’re dehydrated, smoke can dry out your eyes, causing them to appear redder.
  • Cover Them Up: Although it’s cliché, if you’re outside, try wearing sunglasses. This will prevent others from seeing the redness in your eyes.
  • Apply an Ice Pack: Use this simple home remedy for five minutes on each eye to decrease redness.

Talk to Your Doctor About Medical Marijuana

For patients with glaucoma or high blood pressure, marijuana’s ability to lower blood pressure is one of its medical benefits. Although bloodshot eyes can be pesky or embarrassing, it’s nothing to be concerned about. Cannabis is gaining popularity across the nation as a treatment for many medical conditions. It does have a few side effects that should be discussed with your doctor. However, its benefits far outweigh these for most patients.

If you feel medical marijuana would make a good treatment option for you, it’s time to contact a marijuana certified doctor in your state. Our advice shouldn’t replace there’s, so make an appointment today. For specific strain information, contact a dispensary near you to speak with a budtender.

Learn why some cannabis users experience red eyes as a side effect and how to combat side effects to get the most out of your cannabis.