Most of us are familiar with the words “high”, “stoned”, and “drugged”, commonly used on the streets, as well as on television and movies. These are terms used when a person is highly intoxicated owing to some addictive substance, like narcotics, marijuana, or other illicit substance.
However, redness in the eyes is usually specific to someone who has smoked weed, unlike other narcotics in which the pupils dilate. This redness is basically caused by inflammation in the eyes.
But, have you ever wondered why weed causes an inflammatory reaction when CBD – the much-hyped cannabinoid is present in it? Then, does that mean CBD or cannabidiol could have the same effect?
The answer is: No
Fact: The red, watery, inflamed eyes, which is one of the most common and widely noted side effects of cannabis use, is really caused by the THC (∆-9 Tetrahydrocannabinol) in the weed. And, not CBD!
As much as would like to end it here, the answer isn’t quite that simple!
Why Does Marijuana Make Your Eyes Go Red?
Usually, redness of eyes is a sign of an infection, allergy, or exhaustion. However, the redness of eyes caused after smoking weed isn’t caused by any irritation, infection, or tiredness. It’s rather due to your body’s reaction to the psychoactive/psychedelic component of marijuana – THC.
Marijuana has several psychoactive and non-psychoactive chemicals, known as cannabinoids. While THC is the primary psychoactive cannabinoid, CBD is the principal non-psychoactive cannabinoid. While both share similar molecular structure, their atomic arrangement is slightly different. That is why, although they both interact with the same set of receptors in the nervous system, they behave quite differently.
THC’s effects on a person’s mind and body are quite similar to anandamide – often dubbed the “bliss molecule”. Anandamide is a fatty acid neurotransmitter that binds with the same receptor as THC. It makes you feel calmer, happier, even a little excitable at times. And, of course, your eyes turn bright reddish.
THC has the same effect.
In fact, drug peddlers these days often use THC-strong strains to create a more potent variant. This allows them to make more money by selling smaller quantities at a higher price, giving you an even stronger high! This also means you’re more likely to get red eyes.
But then, why does THC make your eyes go bloodshot red?
THC, High, and Red Eyes
THC directly interacts with – or more appropriately attaches to the CB1 receptor in the brain (and eyes, where they are also present). The receptors in the eyes get triggered, making your eyes red.
Behind the scene, THC lowers your blood pressure (quite like anandamide) by dilating the blood vessels. This leads to the intraocular pressure in the eyes to decrease, allowing the little blood capillaries there to open up wide and letting the blood rush in. This is what causes the redness.
Note: Some people may also be allergic to the smoke produced by a particular strain of marijuana. This type of redness is caused by their eyes’ sensitivity to that particular kind of smoke. However, some people are generally allergic to cannabis.
Incidentally, this very side effect can be a good thing for some!
People with a specific kind of eye disease, known as glaucoma, can benefit from using marijuana, which is high in THC. Since glaucoma is caused due to heightened blood pressure, THC can counter that, thus enabling people to recover more easily and faster.
Scientific Reasoning Behind Cannabis & Redness of Eye
Eye’s Intraocular Pressure (IOP) is a complicated thing. Recent studies have indicated that low overall blood pressure does not necessarily result in the lowering of IOP.
In fact, THC and CBD, both of which are known for lowering blood pressure (although at varying levels), they have an opposite reaction on the IOP.
According to Dr. Denise A. Valenti’s 2008 human study, while THC (medical marijuana) can be used to lower pressure in the eye, CBD works to “spike the pressure in the eye”.
In the study, the effects of various doses of THC and CBD administered to six glaucoma patients were compared. The results revealed:
- 5 mg Delta-9-THC Lowered IOP
- 20 mg CBD No effect
- 40 mg CBD Raised IOP
- placebo No effect
A similar Randomized Controlled Trial, published in the Journal of Glaucoma in 2006, and another in the Current Neuropharmacology in 2018 gave similar results.
Although these suggest that glaucoma patients should refrain from CBD, it also supports the understanding that it is THC that causes redness of the eye, and not CBD.
What is CBD? Why Do CBD’s Effects Differ from Weed?
Cannabis plants, irrespective of the strain, contains both THC and CBD – two key cannabinoids that are contrasting in their effects. But what makes each strain of cannabis different from another is the proportion of the cannabinoids, principally THC and CBD. Their synergistic effects are what make each strain specific.
Generally speaking, marijuana contains higher levels of THC than CBD, i.e. they are THC-rich. That is why they are deemed illegal, as they intoxication, dependence, addiction, and most importantly, psychedelic effects.
However, what makes a cannabis strain hemp is its high CBD-content and minimal THC-content. In fact, for a cannabis strain to be legally considered as hemp in the United States, it must contain no more THC than 0.3% of the overall dry weight. In some of these CBD-rich strains, the CBD content can be as high as 20% of the total dry weight. This makes hemp legal in this country.
Reason: A lot of old and recent research studies have proven the safety profile of CBD. In fact, researchers have found CBD to be even safer than most pharmaceutical medications. So much so, CBD is even being considered as a substitute for prescription drugs that have too many adverse effects.
A recent report by the World Health Organization (WHO) supports this view. According to its report “CANNABIDIOL (CBD): Critical Review”, CBD “exhibits no effects indicative of abuse or dependence potential.” The report goes on to say, “…there is no evidence of public health-related problems associated with the use of pure CBD”.
The Way CBD Interacts With Human Body
Like we mentioned earlier, the body’s homeostasis is established and maintained by the endocannabinoid system, along with its receptors and endocannabinoids. These receptors are found all over the central and peripheral nervous systems and communicate with the other receptors there to maintain the balance in processes and bodily functions concerning body temperature, mood, memory, and movement, sleep, hunger, immunity responses, etc. which is called homeostasis.
Apart from the body’s own (endo)cannabinoids, this system can interact with other plant cannabinoids, like CBD and THC. These key cannabis-derived cannabinoids behave differently in our body because of the way they interact with the receptors.
While THC binds directly with the endocannabinoid receptor CB1, thereby directly influencing cognitive and coordinative changes, CBD acts in a more indirect manner.
CBD, however, doesn’t seem to bind directly with either CB1 or CB2 receptors. Instead, it influences a variety of receptor-independent pathways and ion channels to indirectly control the body’s own endocannabinoids to boost their effects, leading to a range of effects that can help improve the body’s overall health.
That is why CBD does not have any effect on the redness of eyes, as it does not directly impact the receptors in the eyes, or for that matter, any other organ or tissue close to it. While CBD has been known to lower blood pressure in some cases, it is suspected that it is caused by traces of THC found in CBD oils, and not CBD itself.
Moreover, it has already been established through Dr. Denise A. Valenti’s 2008 human study that CBD has the opposite effect on the eyes.
Can CBD Help Reduce Redness Caused by Weed?
If you do end up having red eyes due to cannabis use, don’t worry. This is not a permanent effect; neither will it pose a threat to your eyes or your overall health. It can quite easily be resolved.
But first and foremost, it is best to avoid smoking weed that has high THC-content.
Secondly, CBD use DOES NOT cause your eyes to go red as it does in case of THC use. Even though CBD is an anti-inflammatory agent, it still CAN’T DO anything to remove the redness caused by THC use.
If you do use THC-rich strains of cannabis, check out these few things you can do to get rid of those bloodshot weed-red eyes.
Getting Rid of Weed-Red Eyes
Even though the weed-induced redness of eyes is harmless (and can sometimes be a good thing for some people, like glaucoma patients), it isn’t something that others will appreciate when you meet them. So, here are some tips to follow if you’re prone to eye inflammation when you smoke weed:
- Stay hydrated: Drinking plenty of water before, during, and after you smoke weed can help maintain the water level in your body. This will prevent any possible dryness from THC intake you experience.
- Avoid the current strain you’re smoking: Choose a low/no-THC strain. Strains that are high in CBD, CBN, CBG won’t have the same effect as those that are high in THC-content.
- Keep a good eye drop close at hand: This will soothe your eyes. Several brands of eye drops, available in the market, are meant just for this.
You can always wait for it to run its course: Plan your smoking sessions according to your schedule. Smoke when you know you’ll be free and at home. Redness of eyes usually runs its course and does not harm your eyes or have any negative impact on them in the long run.