Effects of THC (Marijuana)
Last Updated Dec 2, 2021
THC interferes with the way the brain normally communicates, creating a variety of effects, notably elevating a person’s heart rate, reducing their inhibitions, and often giving them a sense of relaxed euphoria.
THC, the psychoactive chemical in marijuana, can affect a person’s brain by acting on certain structures of the brain due to its similarities to the naturally occurring brain chemical anandamide.
What Does It Mean to ‘Get High’?
Marijuana is often associated with the phrase “getting high,” although the term broadly applies to the use of most recreational drugs. To “get high” is to use a drug and then feel its effects. The term was originally applied to the euphoric effects of alcohol, although slang has evolved such that we don’t generally use the term in reference to alcohol use anymore.
The main psychoactive ingredient in marijuana is THC. When a person smokes or vapes a substance containing THC, it passes from the lungs into the bloodstream. When smoked, a person generally gets high within a few minutes. If someone instead eats a product containing THC (edibles), the full effect of the drug will take longer to manifest, usually taking somewhere between 30 to 60 minutes to set in.
Smoked marijuana, the most common way THC is absorbed, will create a noticeable effect on a person’s body and mind for about one to three hours, with edibles lasting much longer.
THC’s Effects on the Body
As the body absorbs THC, a person may notice a number of changes occurring. Common effects of marijuana use include the following:
- Drowsiness or sedation
- Bloodshot eyes
- Augmented heart rate
- Increased blood pressure
- Bigger appetite
- Coughing due to lung irritation
Extended use can suppress a person’s immune system, increasing their risk of infection.
A person can also grow dependent on marijuana, with their body undergoing withdrawal if they cease taking the drug. However, marijuana withdrawal is generally mild, with symptoms including the following:
- Decreased appetite
Smoking marijuana has not been linked to cancer in the same way that smoking tobacco products has, although it can still cause long-term breathing problems.
Pregnant people should not use marijuana, as it may affect the development of their child, increasing the risk of certain cognitive problems. Some evidence has also suggested THC can be excreted in breast milk.
THC’s Effects on Mental Health
Marijuana is perhaps most associated with its effects on a person’s mind, often producing a sense of relaxation and reducing inhibitions. It can also heighten sensory perception, changing the way a person appreciates music, art, and touch.
Other mental health effects associated with marijuana, and THC specifically, include the following:
- A distorted sense of time
- Impaired judgment, coordination, and reflexes
- Disorganized thinking or forgetfulness
Less common mental health effects, generally associated with heavy marijuana use, include the following:
- A heightened sense of anxiety or paranoia
- Hallucinations or delusions
- A temporary loss of personal identity
In the long term, marijuana use has been linked to affecting brain development in young people. At least one study showed heavy marijuana use in a person’s teens, where significant brain development is still taking place, may reduce a person’s IQ by an average of 8 points. This change was not seen in people who began smoking weed as adults.
Is Marijuana Dangerous?
Marijuana is under-researched, with its full effects on a person’s health not fully understood. However, moderate use of THC-containing products doesn’t appear to be significantly dangerous.
There are no reported cases of a fatal overdose on marijuana. In addition, the evidence doesn’t currently suggest smoking or vaping marijuana is as dangerous as smoking or vaping tobacco and nicotine products (although many people who smoke marijuana also smoke cigarettes).
At the same time, marijuana use is still associated with certain health risks. It can cause breathing problems when smoked, and it can increase a person’s risk of a heart attack.
Some chronic marijuana users also develop cannabinoid hyperemesis syndrome, which causes a person to experience cycles of severe nausea that sometimes require medical attention due to dehydration. In rare cases, THC has also been known to trigger longer-lasting psychotic disorders, such as schizophrenia, in users already at risk of developing those disorders.
Does THC Have Legitimate Medical Uses?
The official stance of the DEA is that marijuana is a Schedule I substance, marking it as dangerous and with no accepted medical use. They have a less harsh stance on THC specifically, which has approved uses for products that can help with nausea and vomiting in cancer patients and to stimulate the appetite of AIDS patients.
THC solutions can also help in the treatment of anorexia, working as an alternative antiemetic treatment. In addition, an oral solution containing a small amount of THC can be used to treat certain epilepsy conditions.
Many people believe THC, and marijuana in general, has more legitimate medical uses that can be discovered through research. One of the most notable is its potential to help control chronic pain, for which several states sanction its use.
Cannabis (Marijuana). (December 2019). National Institute on Drug Abuse.
It’s Called ‘Getting High’ for This Ancient Reason. (April 2017). Inverse.
Marijuana/Cannabis. (April 2020). U.S. Drug Enforcement Agency.
Medical Marijuana for Children: Advocates Ambivalent About Pediatrics Group’s New Policy On Drugs For Kids. (January 2015). International Business Times.
Cannabis Use and the Risk of Developing a Psychotic Disorder. (June 2008). World Psychiatry.
Cannabinoid Hyperemesis Syndrome. (May 2022). StatPearls.
Effects of Cannabis on the Adolescent Brain. (January 2015). Current Pharmaceutical Design.
Cannabis Use in Pregnancy and Breastfeeding: The Pharmacist’s Role. (March–April 2020). CPJ RPC.
Use of Medical Cannabis in Treating Anorexia and Nausea in Elderly Cancer Patients. (November 2019). Journal of Clinical Oncology.
Cannabinoids in the Treatment of Epilepsy: Hard Evidence at Last? (December 2017). Journal of Epilepsy Research.
What Are Marijuana’s Effects? (July 2020). National Institute on Drug Abuse.
Weighing the Dangers of Cannabis. (August 2019). Nature.
Pharmacology and Effects of Cannabis: A Brief Review. (January 2018). The British Journal of Psychiatry.
Table of Contents