Why Does Cannabis Cause Red Eyes?
Red eyes are probably the most well-known side effect of smoking weed. THC consumption reduces blood pressure and expands the arteries in the eyeball. Special eye drops, available over the counter, promise relief from bloodshot eyes and judgemental looks.
Why does cannabis turn my eyes red? This is perhaps one of the most common questions asked by the average cannabis consumer when first coming into contact with the plant. Cannabis is known to have psychotropic effects and therefore influence behaviour and general frame of mind.
On the other hand, red eyes are known to be the most visible indication that someone has just had a cannabis high. Meanwhile, word has spread so much that this symptom alone – irrespective of its true causes – is often associated with cannabis use.
While this phenomenon obviously has a scientific explanation, the stigma linked to it has increased over the years. Maybe this is because it may have to do with many things, all of which indicate bad health or habits:
- Alcohol abuse
- Even non-abusive tobacco use
But when red eyes show as a result of consuming cannabis, is it in fact a bad thing?
Why do cannabis users get red eyes?
The phenomenon of bloodshot eyes due to cannabis use is primarily the result of the main active substance in cannabis: tetrahydrocannabinol, better known as THC. There is a lot of speculation as to the reason that THC causes eyes to turn red. It may be mediated by direct contact of smoke with the eyes, thus irritating the conjunctiva of the eye. However, tobacco smokers do not experience red eyes, so it’s unclear why cannabis smoking would cause red eyes in this fashion. The conjunctiva may also be aggravated by smoke entering the sinuses, thus causing red eyes this way.
Another hypothesis is that THC affects blood pressure, causing it drop. This results in blood vessels expanding, and blood circulation throughout the body increases. The drop in blood pressure causes the arteries in the eyeball to expand, so the blood is able to circulate more visibly than normal. However, this is inconclusive, as the relationship between THC and blood pressure is complex, and doesn’t affect everybody the same way.
Whilst this side-effect of smoking weed is undesirable for most consumers, it can be beneficial for patients with painful eye conditions such as glaucoma. There is evidence that they feel relief from their symptoms as a result.
While associated with smoking in general, red eyes may also occur irrespective of the consumption method. Vaporizing cannabis or the consumption of food products containing cannabis also have the potential to cause red eyes. This is because THC, one of the main cannabinoids in cannabis, is always activated when the substance is heated to a specific minimum temperature. This is what happens when vaporizing or burning, but also when baking a cookie.
It is also worth noting that there are people in whom the same symptom occurs for different reasons; smoking generally causes red eyes in these individuals, regardless of whether the smoke originates from cannabis or from another substance.
What remedies are available for bloodshot eyes?
From the perspective of an all-round consumer and activist, there’s no reason to conceal red eyes caused by cannabis use. Yet because cannabis isn’t fully accepted either legally or socially, noticeably red eyes will understandably pose a problem for many people.
There is no easy, immediately effective treatment method for red eyes, however. Whereas using one of the available emollients may cause symptoms to disappear entirely in one person, in someone else it may have no effect whatsoever. However, vessel-widening effects can generally be alleviated as follows:
- Use eyedrops; especially those that alleviate inflammation-related redness. They work relatively quickly and often prove to be effective.
- Try vasoconstrictors (vessel-narrowing products) such as: caffeine, chocolate, salty food etc.
- Keep an eye on your eyes and wait. The redness in your eyes will usually subside, provided you haven’t consumed excessive amounts.
If you need perfect, snow-white eyeballs all-year-round for whatever reason, particular varieties that contain different proportions of cannabinoids and terpenoids may be more suitable, especially in relation to red eyes. As ever, we recommend giving different things a go to see what works.
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Are red eyes dangerous?
As long as your red eyes don’t stop you from doing what you need to do every day, you can rest assured that redness doesn’t generally harm your eyes, your brain or your general health. If you become a regular user – for medical or other reasons – your body will become used to the symptom to a certain extent, and the phenomenon will be relatively temporary. However, if you consistently have persistent red eyes that do not seem to go away, there may be an underlying cause that should be addressed by your physician.
Red eyes are a common and undesirable side effect of smoking weed. Special eye drops available over-the-counter promise relief from red eyes.
Why does weed make your eyes red?
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- Under pressure: lower blood pressure and dilated capillaries
- Do edibles make your eyes red?
- 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
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.
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.