Does CBD Cause Red Eyes? Scientifically Explained

Red, inflamed eyes are often the result of many things. These often include common allergies and irritants. They are also a unique side effect of cannabis use. Red eyes can often lead to stigma, embarrassment, and social ostracization. However, cannabis users may reap many medicinal benefits.

Cannabis may ease a litany of conditions and symptoms. Many of the compounds in cannabis contribute to these effects. The cannabis plant is composed of two main components: THC, or tetrahydrocannabinol, and CBD, cannabidiol. THC is a compound with a psychoactive profile. Psychoactive symptoms include the feeling many describe as feeling “high,” as well as paranoia.

THC is also responsible for the bloodshot eyes associated with marijuana. This is because of the rapid rise in blood pressure and then a dramatic drop. The drop in blood pressure causes dilation of blood vessels and capillaries in the eyes. The result is red and inflamed eyes.

In contrast, CBD works in a way that does not affect cognition. Instead, CBD operates within the body by changing how receptors bond with molecules.

This allows for the free flow of neurotransmitters such as serotonin. Serotonin is a critical chemical within the brain. It can combat serious conditions such as depression. Regulation of moods and emotions is crucial to proper mental health and well-being.

What Is CBD?

Although there are hundreds of compounds in marijuana, CBD is one of the main components. CBD is short for cannabidiol. CBD is in many strains of cannabis, though in differing amounts.

For example, in potent THC heavy strains, it can be present in only trace amounts. In high CBD strains, it can account for as much as 20% or more.

CBD’s chemical structure is almost identical to that of THC. The difference lies in one critical element: CBD contains an extra combination of hydrogen and oxygen. This small quirk enables CBD to work without disrupting cognitive processes.

CBD is cited as safe to use in a variety of products. A recent report by the World Health Organization corroborates this by stating that CBD “exhibits no effects indicative of any abuse or dependence potential… To date, there is no evidence of public health-related problems associated with the use of pure CBD.”

How CBD Works

The body must keep processes such as temperature, mood, memory, and movement in check. The ECS, the endocannabinoid system, helps the body in this endeavor.

The ECS is in the peripheral and central nervous systems. It runs throughout the body, collecting data from nerves and immune cells to carry to the brain.

Much of the data delivered to the brain comes from receptors, which act as doorways for several chemicals. THC affects these receptors in the brain, the receptors CB1 and CB2.

When THC causes direct changes to these receptors, a user may experience several effects. These effects may include euphoria, drowsiness, and ‘couch lock.’

While THC stimulates the CB1 receptors, CBD instead acts as an agonist. As an agonist, CBD doesn’t bind directly with any receptor. CBD instead changes the way the receptor connects with a chemical. By altering the receptor’s shape, CBD can influence how the receptor binds to compounds.

The body produces compounds much like those contained in marijuana called endocannabinoids. Endocannabinoids help keep the body’s systems in check. They exert their influence through the body’s ECS, regulating and maintaining essential processes.

Is CBD Legal?

Unlike THC, CBD is legal in the United States. Many products that contain CBD but little to no THC (less than 0.3%) are available for sale in a variety of places. Also, CBD-based products in the United States come from hemp. CBD derived from marijuana is not legal under federal law.

Consumers often take CBD as a therapeutic option rather than as a recreational substance. Individuals frequently buy CBD as an alternative treatment for ailments such as stress, headache, muscle aches, and pain and insomnia. Marijuana is a Schedule I drug and is barred from being consumed or sold by federal law. Individual states have discretion in regulating marijuana.

Despite this restriction, states exercise discretion about the use, consumption and growing methods of marijuana. Some states allow only for the medicinal use of cannabis. Other states have a mix of legislation and permit recreational use. Users must keep advised on the individual laws of their state.


A 2017 study determined that CBD may decrease blood pressure. Blood pressure in the study dropped along with heart rate. The study further suggests that CBD reduces the stress that often accompanies a rapid rise in heart rate.

CBD is also thought to counteract many of the psychoactive effects of THC. This is called the “entourage effect.”

The entourage effect was coined by researchers Mechoulam and Russo. The term describes the process by which substances work together to amplify or heighten impacts on the body.

In high THC, low CBD cannabis strains, users may find that symptoms like red eyes are prevalent. But CBD works against many of the psychoactive characteristics of THC. This reduces the chance a user will develop red eyes. Those with a low tolerance for THC should use a high CBD strain or take CBD alone.

When consumers are choosing a CBD product, there are two available options: Full-spectrum or isolate. Full-spectrum CBD contains all the components present in marijuana, save the THC. This includes terpenes, flavonoids, and essential cannabinoids.

Using a full-spectrum CBD is the best way to enjoy many of the benefits of cannabis without the risk of psychoactive effects. CBD isolate is a CBD formula with no other compounds. It may still be very beneficial for health and well-being.

Getting the Red Out

Users can minimize the risk of red eyes that occurs with THC. Methods include proper hydration, rest, using an eye drop, or changing strains. However, none of these techniques can guarantee that red eyes will not be a problem.

Taking CBD is a way that individuals can get many of the therapeutic effects without suffering from red eyes. Due to the way CBD works with receptors, dilation of vessels and capillaries does not occur.