Red Eyes: How to Tell If They Are from Marijuana Use or Something Else

Medically Reviewed

Marijuana is the most common illicit drug in the United States, and in some places, it’s legal to use for medical and even recreational marijuana. It’s currently the easiest illicit substance to obtain in the United States, and it’s especially popular among young men. According to the 2015 National Survey on Drug Use and Health, more than 22 million people reported using the drug within the past month.

According to the same study, more than 36 percent of 12th-graders reported using marijuana in the past year. Teens’ perception of the risk of marijuana is also in decline, partly due to the public debate about cannabis laws and the relative safety of medical marijuana. However, illicit cannabis and synthetic drugs used to mimic the effects of marijuana can be dangerous and unpredictable.

Since marijuana is the most popular illicit drug in the United States, especially among young adults and teens, parents and loved ones often want to know what signs they can look for that may point to cannabis use. However, the signs and symptoms of marijuana use may mimic other common ailments, and it’s wise to avoid putting your loved ones through inquisitions every time they get a cold. However, illicit drug use early in life, especially in childhood or teen years, can increase your likelihood of experiencing a substance use disorder later in life.

One of the telltale signs of marijuana use is red, bloodshot eyes. But red eyes are also a sign of allergies, colds, contact irritation, pink eye, and many other everyday ocular issues. How can you tell the difference between redness caused by weed and common causes?

Learn more about the signs and symptoms of marijuana use and how you can help loved ones who may be struggling with a substance use disorder. 

Why Does Marijuana Cause Red Eyes?

Most people have experienced red or bloodshot eyes for one reason or another, especially since it’s a symptom of ubiquitous ailments such as fatigue and seasonal allergies. The symptom is fairly similar whether your eyes are red from pollen or cannabis. However, weed doesn’t cause red eyes because of irritation (unless you’re getting a lot of smoke in your eyes). Instead, marijuana causes red eyes because of a biological reaction to the psychoactive drug in your system.

The exact cause of bloodshot eyes in cannabis users can be complicated. Marijuana has several active ingredients called cannabinoids that can have different effects on the user. Different strains of cannabis can have varying levels of these cannabinoids, which is why marijuana can seem to have widely different effects on individual people at different times.

The cannabinoids in marijuana can start to affect your blood pressure and heart rate. About five minutes after you smoke marijuana, your blood pressure will drop, and your heart rate will be lowered. These effects will dilate your capillaries, which means your blood vessels will become wider, allowing more blood to pass through them. This causes a rush of blood to your eyeballs.

One of the active cannabinoids in marijuana is called tetrahydrocannabinol (THC). It’s the main cause of the drug’s intoxicating effects. THC is believed to cause similar effects in the brain and body as a substance called anandamide, which is a fatty acid that binds to the same receptors as THC. Anandamide works to dilate blood vessels and lower blood pressure. It’s thought that THC works in the same way. Marijuana with a higher THC content is more likely to cause bloodshot eyes. You are also more likely to have bloodshot eyes after a large dose or repeated use in close succession.

Illicit marijuana is becoming more and more potent because strains are being made with more THC and less cannabidiol (CBD). THC is what causes the high and euphoric feeling in marijuana, so drug dealers work to create more potent versions so that they can up the price for a smaller quantity. This also allows them to transport valuable amounts in smaller, harder-to-detect packages. For that reason, you are probably more likely to get red eyes from illicit cannabis than from medical marijuana. However, it can happen with both.

Though the reason for red eyes in cannabis users may be different from irritation, they can both be treated using eye drops. Over-the-counter drops used to moisturize dry eyes can also counteract the redness in bloodshot eyes caused by marijuana. 

Know The Difference

Since redness from marijuana use is so similar to redness from other common ailments, is it possible to tell the difference? Based on the state of a person’s eyes alone, you probably wouldn’t be able to definitively identify someone who’s using marijuana versus someone who has dry eyes. However, since red eyes are usually a symptom of particularly potent marijuana, it will typically come with other noticeable symptoms. On the other hand, it’s possible to use marijuana without displaying any obvious symptoms, so it’s important to speak to your children and loved ones about safe drug practices and the risks of using marijuana and other illicit substances, whether or not you notice symptoms.

Marijuana has a long list of subjective effects. The three major cannabinoids — THC, CBD, and cannabinol — all have unique effects that can be more present in marijuana depending on the levels of each of these chemicals in the strain. However, cannabis causes a few common effects, including dry mouth, clammy skin, impaired motor skills, increased heart rate, and muscle relaxation.

Cannabis can cause deep relaxation and euphoria that leads to subjective psychological or physical effects. Marijuana can also create an altered state of consciousness, increased libido, and a distorted perception of time. In higher doses, users may experience audio or visual hallucinations, reflex impairment, and ataxia. Other telltale signs may include increased appetite and impairment of short-term memory.

Because the effects of marijuana can be different for each person, it can be challenging to identify. If you do believe that a loved one is using any illicit drugs, a conversation with them might be more telling than symptoms. People struggling with addiction often lie about drug use, hide drugs around the house, and keep their schedule and friend groups secret. Substance use becomes a problem when it starts to interfere with daily life. Failing work or school performances, relationship issues, and strange sleep schedules can also be general signs of substance addiction. If you or someone you know displays any of the signs of a severe substance use disorder, they may need professional help to overcome it. 

Seeking Help For Substance Use Disorders

Marijuana isn’t a chemically addictive drug, but it can lead to psychological addiction. Plus, exposure to illicit and psychoactive substances earlier in life is a risk factor for developing a substance use disorder later in adulthood.

If you or someone you know is struggling with a substance use disorder related to marijuana or any other substance, there is help available to give you more information about addiction treatment. Speak to an addiction treatment specialist at Serenity at Summit to learn more about addiction treatment options that might be available to you.

Call 844-432-0416 to hear about the addiction therapies that may be able to lead you or your loved one to long-lasting sobriety. A call may be your first step on the road to recovery.

Tap to GET HELP NOW: (844) 326-4514