Medically Reviewed by
Jason Crawford

Article Last Updated on January 1, 2023

Following the legalization of cannabis in some states in the United States, the number of people using marijuana for medical or recreational reasons has been increasing, and so has the curiosity about the cannabis plant and its chemical composition. This has led to increased research and new insights into how marijuana can affect mental health and physical health.

In this article, we’ll primarily talk about the short-term effects caused by marijuana in detail, and we’ll also touch upon the effects caused by long-term marijuana use and the health risks.

How Marijuana Interacts With the Human Body

Marijuana has a rich chemical structure. It contains hundreds of cannabinoids, terpenes, and flavanols that contribute to its unique properties, flavor, and aroma. The two most important cannabinoids are CBD (cannabidiol) and THC (tetrahydrocannabinol or delta-9-tetrahydrocannabinol). THC is a psychoactive cannabinoid that produces mind-altering effects and it’s largely responsible for experiencing the “high,” while CBD is non-intoxicating and is primarily used for medical purposes.

Marijuana can belong to three species of the cannabis plant – Cannabis indica, Cannabis sativa, or hybrid if it’s a combination of both. Different marijuana varieties have different ratios of CBD and THC which make them produce different effects. Strains higher in THC, for example, are more likely to produce side effects.

These cannabinoids interact with the body’s endocannabinoid system, which is a network of cannabinoid receptors located throughout the body, including the central nervous system and the immune system. The endocannabinoid system is important because it participates in crucial processes in the body, like anti-inflammatory response, learning and memory, sleep and mood regulation, among others.

Smoking marijuana is by far the most common method of marijuana consumption, though just like tobacco smoke, marijuana smoke is known to irritate the lungs and can be especially aggravating for people with bronchitis or other respiratory issues.

What Are the Short-Term Effects of Marijuana?

If you’re a marijuana enthusiast, you must be familiar with the ins and the outs of being high. The effects produced by THC (the psychoactive cannabinoid) include euphoria and a feeling of bliss and calmness. However, there are times when you can also experience anxiety, including red eyes and increased thirst as side effects of too much THC. CBD, as a non-intoxicating cannabinoid, serves to balance out the effects of THC, and overall, it produces calmer and more mellow effects without getting you high. CBD-dominant strains are more often used for medical purposes or for general wellness for people who don’t like the THC-induced high. 

But aside from that, let’s see how marijuana affects certain mental and bodily functions in the short term and why they happen.

Memory Impairment

There are many cannabinoid receptors in the hippocampus, the part of the brain largely responsible for memory forming, and the THC present in marijuana can significantly impact these functions in the human brain.

Recent studies on the effects of marijuana suggest that recreational use can cause impairment of short-term memory in marijuana users, which affects learning ability (non-verbal learning) and retaining new information.

One clinical study indicates that short-term memory impairment is predominately dose-dependent. The short-term memory task performances of the participants in the study demonstrated that the higher the THC concentration in the weed was, the lower the short-term memory task performance was. However, another study concluded that memory impairment can be regained with a few week’s abstinence from marijuana use.

On the flip side, though, strains that are higher in CBD and lower in THC show major promise for the treatment and prevention of neurodegenerative diseases like Alzheimer’s, and research acknowledges this. The paradox lies in the CBD to THC ratio, where CBD can mitigate the exaggerated effects of THC and stimulate the brain in a more beneficial, non-intoxicating way.

Lowered Anxiety

It’s common knowledge that many individuals use cannabis as medical marijuana to help treat stress and symptoms of depression and anxiety. A clinical study published in the Journal of Affective Disorders has found that medical cannabis users had a reduction of depression by 50% and a 58% reduction in anxiety by smoking marijuana. 

They found that two puffs were the most effective for depression and anxiety and 10 puffs or more to relieve stress. It was also found that strains with lower THC content and higher CBD content were more successful in reducing the symptoms of anxiety. Additionally, strains that had a balanced ratio of THC and CBD reduced the symptoms of stress as well.

The mechanism behind this effect of marijuana is that the cannabinoids bind to receptors present in the amygdala, the part of the brain responsible for the threat response, and help to stabilize its function, which results in a calmer mood.

Additionally, THC works in the parts of the brain that are mainly responsible for feelings of reward and pleasure. It stimulates the release of dopamine, the neurotransmitter that regulates mood and produces the euphoric feeling associated with cannabis use.

Difficulties with Coordination

Marijuana affects the parts of the brain that regulate the coordination of movement and motor control. Users who smoke marijuana know that getting high often results in poorer motor control. It has been found that cannabis use is associated with motor performance impairments. One clinical trial has found that high concentrations of THC affects orientation and motor coordination.

The National Institute on Drug Abuse reported that the effect is even worse when weed is combined with alcohol. According to them, such substance abuse can significantly impair driving ability, therefore it’s recommended to not mix weed and alcohol when driving.

Bigger Appetite

If you’re a regular marijuana user, you must be familiar with the munchies. This is one of the most common side effects caused by cannabis and one that can affect you either positively or negatively, depending on the reasons for your marijuana use. Some medical marijuana users find munchies beneficial if they’re trying to restore their appetite.

Studies show that THC is largely responsible for the increased hunger that comes with weed use. Essentially, by binding to certain cannabinoid receptors, it stimulates the hormone that increases appetite and it can even influence the food choices that you make. You may get specific cravings for sweet, salty, or sour foods, and end up eating more calories than usual.

Increased Heart Rate

Cannabis is known to significantly elevate the heart rate within the first 15 minutes of consumption when the THC reaches its peak. During this time, the heart rate may increase up to 50 beats per minute or sometimes it may even increase by 50%. The heart rate stays elevated for up to 3 hours after consumption, meaning that there is an increased risk of a heart attack. This especially applies to seniors and people with heart disease.

Reduced Pain

One of the most common uses of marijuana is for pain relief. Many people use cannabis to ease the pain caused by a variety of health conditions. Even though research on this topic is still ongoing, there have been many clinical trials that have examined this effect of marijuana. One study published in the journal Complementary Therapies in Medicine concluded that strains that are higher in THC can act as an effective analgesic. Their results indicated that the momentary pain intensity in average cannabis users drops by 3 points on a scale of 1 to 10.

What Are the Most Common Long-Term Effects of Marijuana Use?

There is more limited information regarding the long-term effects of marijuana compared to the short-term effects, but there is some evidence for some health problems that can be caused by weed. One example is the effect of long-term marijuana use on brain development. Adolescents who abuse marijuana at a young age are especially vulnerable to the effects of marijuana because their brains are still not fully formed and it can lead to serious consequences.

One study argues that there are possible “cognitive and emotional deficits” in teenagers that are heavy users of cannabis. Similarly, a review of literature on the effects of cannabis on the adolescent brain concludes that chronic marijuana use in adolescents can lead to cognitive impairments and an increased risk of psychiatric disorders.

Finally, long-term marijuana use can also increase the risk of developing schizophrenia for people who have a family history of a mental illness of this kind. 

Does Marijuana Cause Addiction?

You may be wondering if marijuana addiction is a thing since there are many who say that marijuana can’t cause addiction, but this is not true. Marijuana can, in fact, cause dependence and this is most strongly felt when you stop taking it. Users often feel withdrawal symptoms that can last between one to two weeks, and this can decrease with each day. The intensity of the withdrawal symptoms largely depends on the frequency of marijuana use.


Despite all the beneficial effects that marijuana can be used for, moderation and responsible use is the key to getting the most out of it. That said, no substance is safe in excessive amounts, and neither is cannabis. Irresponsible substance use can lead to many undesirable side effects, so as long as you’re informed about all the side effects of cannabis, you’re more likely to use it in a way that will be beneficial for you.

Additional Sources

Volkow, N. D., Baler, R. D., Compton, W. M., & Weiss, S. R. (2014). Adverse health effects of marijuana use. The New England journal of medicine, 370(23), 2219–2227. https://doi.org/10.1056/NEJMra1402309

Winters KC, Lee CY. Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age. Drug Alcohol Depend. 2008;92(1-3):239-247. doi:10.1016/j.drugalcdep.2007.08.005

NIDA. 2019, December 24. Marijuana DrugFacts. Retrieved from https://www.drugabuse.gov/publications/drugfacts/marijuana on 2021, January 21

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.