statistics of bloodshot eyes from marijuanas

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.

Why Your Eyes Turn Red After Smoking Cannabis?

Thursday 23 August

The Eyes Don’t Lie – Especially When You’re High

Why cannabis causes red eyes and what to do about it

We’ve all been there, and we all know what it looks like: red eyes caused by consumption of cannabis. It’s a tell-tale sign for the practiced smoker, allowing instant recognition of fellow marijuana fans, but it is also the main giveaway for concerned parents, suspicious cops, and perceptive teachers – makes you wonder where they learned to recognise the symptoms, don’t you agree?

Since before the days of ancient Greece, the eyes have been described by poets and philosophers as ‘mirrors of the soul’. Our eyes convey a lot of information about how we feel, especially to someone who knows what to look for. This seems doubly true when we’re high: red eyes can be caused by many different things, but a good joint will certainly do the trick. In this article, we look at the causes of the phenomenon, as we try to figure out a way to work around it and perhaps hide your high from nosey onlookers…

So are red eyes harmful?

Nope, there’s no harm whatsoever in the ‘red eye’ marijuana phenomenon. We can be brief about this. Red eyes are a perfectly natural reaction of your body’s cardiovascular system to the effects of tetrahydrocannabinol (THC), which is present in just about all strains and variants of weed and hash. THC has the ability to connect with certain receptors in your nervous system, and that is how smoking a joint or eating a hash muffin affects your behaviour and biology. THC interacts with your heart and blood vessels as it does with many other parts of your body, most notably your brain. So why does your high show in your eye? Let’s expose the mechanism that is responsible for this classic stoner characteristic.


Speaking in fancy medical terms, cannabis causes red eyes through vasodilation. This is a fancy word for the widening of blood vessels and capillaries, and it is triggered by tiny muscles relaxing around the vessels themselves, allowing them to expand. This widening of the blood vessels serves to lower blood pressure, because if the heart keeps pumping blood around at the same pace, it can flow more easily through the broadened corridors of your vascular system, requiring less pressure to do so. These processes occur at the subconscious level, so we have no power over vasodilation or its opposite, which is called vasoconstriction. They are autonomous responses triggered by your nervous system, of which the so-called endocannabinoid systemis a part. As you may know or may have guessed from the name, cannabinoids present in cannabis plants can interact with this endocannabinoid system. If we get enough THC in our blood, it changes activity levels in many parts of our body. It’s just how our nerves respond to cannabis. Right after smoking a joint, people experience a brief increase in heartrate and blood pressure (through vasoconstriction), followed by a drop in heartrate and vasodilation. Now, this is when the eyes go red, because the capillaries just beneath the surface of the white in your eyeball expand. Being wider, they can contain more blood, which in this case is bright red because it carries fresh oxygen to the tissues. The tiny blood vessels in your eye will become more visible as a result, and because they are so small, anyone standing nearby will see a pinkish-red glaze where the white of your eyes used to be. Some researchers claim that more THC will cause more reddening, so you could even use your red eyes as a way to test the potency of your weed – at least in theory. So there you have it: the red is perfectly normal for smokers. Nothing unhealthy or dangerous; just a normal response beyond your control. When the high has passed, your heart rate and blood pressure return to normal, your blood vessels constrict again, and the red is gone.

Hiding Red Eyes

Since vasodilation is an autonomous process that you can’t control no matter how hard you try, it seems as if there is nothing you can do about red eyes. Fortunately, medical science has come up with a few handy tricks for any stoner aiming to keep a low profile. The first of these are chemical eye drops. They were originally developed to relieve temporary discomfort for anyone suffering from irritated eyes and allergies, but hey! Red eyes after smoking are definitely not an allergy symptom, but being super aware of your stoner look can be irritating, so this trick seems legit!

A milder solution is to use artificial teardrops, sold over the counter at any pharmacy. These are intended for people trying to get rid of dry eyes, but they soothe the tissues to such an extent that the redness will go away, even after a good smoke. Keep a bottle of this stuff handy and simply apply a few drops to your eyes. The redness will be gone in a few minutes. All you need to do now is try not to betray yourself by getting the munchies and launching an all-out assault on the fridge!

Of course, there is an easier and non-medical way to hide your red eyes, and that is a stock inventory item of any smoker: sunglasses! They’re trendy, they’re fairly inconspicuous, and they fit in any handbag. Put simply, don’t leave home without them if there is even a slight chance of smoking up ahead.

Out Of The Red

So there we go. We now know that red eyes are a perfectly natural and harmless response to THC in your system. We also know what causes it at a biological level, as well as finding a few easy ways to cover them up. Its seems as though nothing can stop us from enjoying a nice spliff without anyone noticing, so go ahead – enjoy it!

Everybody knows the fact that the eyes will turn red after smoking cannabis. Why do your eyes turn red after smoking cannabis? Read it here..