A breakdown of what happens when you smoke marijuana or consume edibles. How does marijuana affect your brain and body?

Have you ever wondered what happens in your brain and body when you smoke marijuana or consume a pot brownie? The negative effects are obvious, but what is occurring physiologically to produce these sensations? And why do other individuals experience completely different effects from marijuana, such as anxiety or paranoia? What effect does marijuana have on the brain? How does cannabis impact the body?

Inquisitive about the acute effects of cannabis for the occasional adult user, we asked two leading researchers in the field to break down the effects of inhalation (or ingestion), intoxication, and coming down from the high.


The Cannabis sativa plant contains hundreds of distinct compounds in variable concentrations, depending on the strain and the method of cultivation. THC, or delta-9-tetrahydrocannabinol, is the psychoactive cannabinoid that recreational marijuana consumers are most interested in. In general, the greater the THC concentration, the more potent and more intoxicating the cannabis.

Dr. Staci Gruber, Ph.D., director of the Marijuana Investigations for Neuroscientific Discovery program at McLean Hospital in Massachusetts, believes that producers currently engineer plants to generate large amounts of THC. Currently, marijuana is about 300 percent stronger than it was in the mid-1990s.

“THC content has skyrocketed, but CBD and other elements that may offset the harmful effects of THC have decreased,” she explains. The ratio between THC and other chemicals increased from 14 to 1 to 100 to 1. This ratio is important because it determines the precise effects of marijuana on the brain and body.

The endocannabinoid system consists of substances and receptors present throughout the body. “Every single cell and organ system contains endocannabinoid receptors,” says Daniele Piomelli, M.D., Ph.D., head of the Center for the Study of Cannabis at the University of California, Irvine. However, the highest concentration is in the brain.

THC binds to and activates CB1 receptors, which regulate mood, metabolism, memory, and locomotion. Activation of CB1 is responsible for the majority of marijuana’s acute effects on the brain and body, at least those that are felt.


So you drew deeply from a blunt. How does marijuana affect your brain and body? The first thing to understand is that the effects of smoking marijuana differ slightly from those of eating it.

“When cannabis is inhaled, the kinetics, or the rate at which effects occur, are quite rapid,” explains Piomelli. “It immediately enters the lungs, circulates via the heart, and ascends to the brain. However, it wears off more fast than other methods of cannabis consumption.”

The cardiovascular effect is the first to be felt. “Blood pressure lowers,” Piomelli says. “As an initial response, the heart pumps more blood to restore normal blood pressure, resulting in an increase in heart rate. These undesirable effects are the primary reason why first-time cannabis users dislike the substance. They feel dizzy and frightened as a result of their rapid heartbeat, but these sensations pass soon.”

The high follows, as THC goes to the brain and activates CB1 receptors. “When there is enough THC in the brain to activate enough endocannabinoid receptors, you get that stoned feeling of euphoria and intoxication that is unique to cannabis,” explains Piomelli.

This procedure, according to Gruber, triggers the brain’s reward system, producing a reinforcing effect: “You receive a rush of dopamine, which causes pleasure and makes you feel good.”


When cannabis is ingested as food, the sequence of events differs slightly, and it often takes 60 to 100 minutes to feel the effects, as opposed to mere minutes when smoked, according to Gruber. Clearly, this cannabis brownie escapes the lungs, but it must be digested before the THC can be absorbed and sent to the brain.

Before reaching the brain, THC must first pass through the liver. Piomelli explains that there, it is digested and transformed into 11-hydroxy-THC, a more powerful molecule than THC. This more potent form is then transported to the brain.

Intriguingly, cisgender women produce 11-hydroxy-THC more efficiently than cisgender men, making most women more sensitive to cannabis consumption. “It is common knowledge that men like cannabis more than women, and it is not because our brains are different,” explains Piomelli. “This is primarily due to the fact that our livers are different and women have more active metabolisms, allowing more 11-hydroxy-THC to reach the brain.”

THC is a chemical that resembles fat, so once it reaches the fatty brain, it stays there for a while. “After a few hours, the first high begins to fade, and one of the side effects is feeling hungry,” explains Piooelli. “However, this is not true hunger; rather, it is a heightened appreciation for the sensory characteristics of food. It is difficult to quit eating since everything you are eating tastes so delicious.”

The good news, he continues, is that THC has no residual effects after it leaves the brain. “As the effects of marijuana wear off, it does not induce a strong desire for more.”


Despite the fact that everyone who smokes or consumes cannabis undergoes the same biological processes, the way these processes affect people’s emotions differs greatly.

“Some individuals are extraordinarily sensitive to THC, while others are less so,” adds Gruber. “Some become highly paranoid, while others have no issues. Some people exclaim, “Oh my god, I was so hungry that I ate everything in the house,” yet others never feel hungry. If someone delivers you a bowl or a vape cartridge of Granddaddy Purple, you will very certainly have a different experience than they do, despite smoking the identical substance.

There are numerous possible explanations for this. “So much of it depends on prior experience with THC and other narcotics,” Gruber explains. “It also relies on your specific body chemistry and metabolism, as well as the product itself, such as whether it is a cultivar with high levels of other cannabinoids that counteract the effects of THC.”

The level of activation of a person’s endocannabinoid system prior to cannabis consumption is also a factor. “Let’s assume that 70 percent of your receptors are activated and just 20 percent of that person’s receptors are activated prior to using marijuana,” Piomelli explains. “As a result of this difference, you may have anxiety after smoking, whereas the other person feels more at ease.” This also explains why the same individual may experience various effects on different occasions despite consuming the same product.

Due to the presence of so many uncontrollable variables, Gruber encourages adults with limited marijuana experience, as well as seasoned users experimenting with novel products, to “start low and go slow” to determine their reaction. She says, “You can always add more, but you can never subtract.”

We hope you enjoyed reading our article on how does marijuana affect your brain and body.


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