How Marijuana Affects the Body and Brain

Discover how marijuana affects the body and how marijuana affects the brain. Plus info on the effects of marijuana on the body and brain.

Marijuana is a psychoactive drug, a preparation of the leaves and flowers of the cannabis (cannabis sativa) plant. Marijuana affects the brain and the body. Over 400 active compounds have been found in the cannabis plant, 60 of which are unique to marijuana. The chemical compounds found in cannabis are collectively known as cannabinoids. Marijuana affects the brain primarily through the psychoactive compound delta-9-tetrahydrocannabinol (THC), referred to as THC.

Marijuana Effects - Marijuana Effects on the Body

Marijuana affects the body in a variety of ways. Marijuana effects on the body include effects to the:1

  • Immune system
  • Heart
  • Lungs
  • Reproductive system

Marijuana's physical effects on the heart are typically seen in new users. A 20% - 100% rise in heart rate can be seen and it may last 2 - 3 hours. Other marijuana effects on the body, specifically the heart, include possible heart attack, heart failure and stroke in those with additional risk factors.

More detailed information on short-term and long-term effects of marijuana.

Marijuana Effects - How Smoking Marijuana Affects the Body

Smoking increases the marijuana effects on the body. A marijuana cigarette (joint) contains all the compounds found in a tobacco cigarette except the nicotine and because joints do not contain a filter, smoke from marijuana affects the body more negatively. One study found that over an 8-year period, respiratory health showed a greater decline among marijuana smokers than among tobacco smokers. When marijuana is smoked, 1/3 more tar is deposited into the respiratory tract compared to tobacco smoking.

Additional smoking-related marijuana effects on the body include:

  • Cough, wheezing
  • Bronchitis
  • Emphysema
  • Cancer

Marijuana Effects - Brain Effects of Marijuana

It was not until the 1990s that cannabinoid receptors in the brain, responding to THC, were discovered. Marijuana affects the brain primarily through these cannabinoid receptors, known as CB1 and CB2.

CB1 receptors are found, primarily, throughout the brain. Through THC's interaction with CB1, marijuana affects brain areas relating to higher functioning, memory, cognition, movement and brain reward. CB1 receptors are also responsible for brain effects of marijuana involving:

  • Anxiety (read: anxiety and marijuana)
  • Pain
  • Sensory perception
  • Motor coordination
  • Endocrine function (impacts hormone secretion)

CB2 receptors are found more peripherally and produce marijuana effects on the brain involving the immune system, peripheral nerve and the vas deferens (involved in sperm ejaculation).

Both CB1 and CB2 interact with other neuron components resulting in one of the brain effects of marijuana being a decrease in other brain chemicals (neurotransmitters) like: acetylcholine, glutamate, norepinephrine, dopamine, serotonin and gamma-aminobutyric acid (GABA).

Marijuana Effects - Marijuana Psychological Effects

Due to the marijuana effects on the brain, there are many marijuana psychological effects as well. The primary desirable marijuana psychological effect is that of feeling "high." Marijuana effects on the brain create a high associated with:

  • Feelings of intoxication and detachment
  • Relaxation
  • Altered perception of time and distance
  • Intensified senses
  • Laughter, talkativeness
  • Decreased anxiety and alertness
  • Depression (read: marijuana and depression)

There are less desirable marijuana psychological effects and these are more likely to be experienced by new users. Marijuana effects on the brain also create feelings of:

  • Anxiety, panic, paranoia
  • Altered perceptions
  • Mania
  • Psychosis

article references

APA Reference
Tracy, N. (2021, December 15). How Marijuana Affects the Body and Brain, HealthyPlace. Retrieved on 2024, June 25 from

Last Updated: December 30, 2021

Medically reviewed by Harry Croft, MD

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