Medically Reviewed by
Jason Crawford

Article Last Updated on January 13, 2023

Marijuana has been used for tens of thousands of years, dating back to ancient civilizations in China, Egypt, India, and the Middle East. These days, thankfully, weed is slowly returning to the front due to new research being done which is how more people learn about its health effects.

Weed is such a complex plant that we need a lot of research to cover every aspect, but at the same time, what we currently know is very satisfying as we have scientific evidence about a number of things that cannabis is beneficial for.

In this article, we’ll talk about the aspects of cannabis that are beneficial for your health, and also the health risks associated with the use of marijuana.

An Overview of Weed and Its Active Ingredients

Weed has a complex chemical structure comprised of hundreds of different compounds. The most important and well-known ones are the cannabinoids, followed by the terpenes.

Cannabinoids are the “trademark” active ingredients of cannabis because they produce the effects that weed is known for, THC (tetrahydrocannabinol) and CBD (cannabidiol) being the two most important ones. THC is psychoactive and produces the famous euphoria, while CBD isn’t intoxicating and it has therapeutic effects. The terpenes are aromatic compounds that complement the cannabinoids.

THC and CBD are largely responsible for the health effects of weed. THC has sedative and anti-inflammatory properties and can relieve nausea, while CBD has therapeutic, anti-inflammatory, analgesic, anti-anxiety, anticonvulsant, and antipsychotic properties and is used to treat many conditions.

When you consume weed, the active ingredients attach to the cannabinoid receptors in your brain and the rest of the body and modify their function. This is how you start to feel the effects of cannabis.

The Health Effects of Cannabis

The legalization of weed has opened up opportunities for research that weren’t there before. One highlight is an extensive 2017 review done by the National Academies of Sciences which examined over 10,000 scientific abstracts published since 1999. Additionally, the National Institutes of Health (NIH) has funded research on the medical use of cannabis and its components.

Even though there is a lot left to discover of the cannabis universe, we still have a substantial amount of information regarding the health benefits of cannabis, at least enough for medical cannabis to be approved for use in 36 states as of 2021.

Let’s review the health effects of cannabis on both physical and mental health.

Chronic Pain Relief 

Chronic pain is a very common symptom of a myriad of medical conditions and millions of people suffer from it. Cannabis is well-known for its ability to provide chronic pain relief. The anti-inflammatory properties of the cannabinoids can alleviate the discomfort and help to manage the symptoms, as well as help patients sleep better. For example, research shows that it can be very effective for fibromyalgia, a chronic pain condition that causes widespread pain.


One major breakthrough was the discovery that CBD can help to control the symptoms of two rare and severe forms of epilepsy called Lennox-Gastaut and Dravet syndromes. In 2018, the U.S. Food and Drug Administration (FDA) approved the medical use of CBD oil, sold under the name of Epidiolex as a medical-grade CBD oil.

Muscle Spasticity 

The use of cannabis has also proven to have therapeutic effects on muscle spasms caused by multiple sclerosis. A 2020 review states that cannabis-derived drugs, such as Nabiximols, a cannabis extract spray that was approved for use in 2010, can reduce multiple sclerosis-related muscle spasticity. 

Motor Function

There is some proposal that medical marijuana can also be used to relieve some of the symptoms of Parkinson’s disease. Cannabinoids THC and CBD may have neuroprotective benefits that top the progressive degradation of neurons. However, more research is needed before it can be officially used for this condition.

Anxiety Disorders

Cannabis has anxiolytic (anti-anxiety) properties thanks to CBD and its therapeutic effects. Anxiety is a very common condition, and both anecdotal and clinical evidence shows that it can help your mental health.


Depression is another very common condition, and similarly, cannabis can help treat the symptoms and is usually better tolerated than common antidepressants. Research has shown that weed can provide short-term relief from the symptoms, but it hasn’t yet been examined how long-term use of marijuana impacts depression.

Post-Traumatic Stress Disorder (PTSD)

In a number of states, medical marijuana is prescribed for PTSD as it has been proven that it can control the symptoms. One of the more common symptoms of PTSD is having nightmares, and the THC in cannabis reduces the time spent in a dream state. A 2020 research concluded that individuals who use medical cannabis are more likely to recover from PTSD in one year.

Attention Deficit Hyperactivity Disorder (ADHD)

Even though more expansive clinical studies are needed, some research suggests that cannabinoids can be beneficial for ADHD. A 2017 clinical trial has found that a cannabinoid-based experimental medicine helped reduce the symptoms of ADHD without causing any cognitive impairments.

What Are the Health Risks Associated With Weed?

Much like all substances, weed isn’t perfect, and in some situations, it can cause some negative effects. The negative effects of marijuana can be either dose-dependent or occur as a result of overuse, or in cases when there is a pre-existing medical condition.

Respiratory Conditions

Even though weed smoke has not been associated with chronic obstructive pulmonary disease (COPD) like tobacco smoke, smoking marijuana can still have some negative effects on the lungs, such as causing chronic cough and phlegm, as well as chronic bronchitis episodes. Ceasing to smoke weed seems to resolve these issues.

Mental Health Conditions

While weed can be very beneficial for depression and anxiety, in individuals who are genetically prone to psychosis, frequent marijuana use can trigger mental illnesses like schizophrenia.

Additionally, individuals who suffer from bipolar disorder are advised to not use weed as a form of treatment as it has been found that it can exacerbate the condition.

Heart Attack Risk

Smoking weed may lead to an increased risk of a heart attack in individuals who have heart conditions or who lead a sedentary lifestyle. It has been observed that weed increases the chances of getting a heart attack within the first hour because THC temporarily increases the heart rate.


Even though there isn’t enough research on using marijuana during pregnancy and breastfeeding, some studies suggest that THC can have a negative impact on the baby’s development. Therefore, even with the lack of concrete evidence, mothers-to-be are usually discouraged from using weed while they’re pregnant and breastfeeding.

Brain Development

Some studies propose that heavy weed use in adolescence, while the brain is still developing, can leave long-term effects on neurocognitive performance which can result in decreased functions such as attention, memory, and processing speed. This effect of marijuana needs to be looked into more thoroughly.

Marijuana Use Disorder

Marijuana isn’t considered a highly addictive substance like opioids, nicotine, or alcohol, but in a small percentage of marijuana users, it can cause dependence. According to the National Institute of Drug Abuse, around 30% of weed users “have some degree of marijuana use disorder,” with those that have started using it in their adolescence being at a much higher risk.

Driving Safety

While weed produces some very pleasant feelings and can help you not only medically but also to relax and enjoy yourself, it also causes motor and judgment impairment. These effects can make you unfit for driving safely and may put you and others in danger. 

In fact, Newsweek reports that according to 2021 research, in California, Colorado, Nevada, Oregon, and Washington, where the recreational use of weed is legal, there has been an overall spike in car crash rates.

Bottom Line

Weed has been used for such a long time and only in recent decades did we have the opportunity to examine it closely. The effects of weed are all due to the active ingredients THC, CBD, and other cannabinoids that work together to enhance its effects. Weed can be used to alleviate the symptoms of many conditions and it can also help mental health.

But, for all the positive effects, weed still has some limitations that, just like its medical benefits, need to be examined more closely so that we can have the full picture from all angles.

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.