Medically Reviewed by
Jason Crawford

Article Last Updated on January 2, 2023

The use of cannabis and cannabinoids for treating medical conditions was popular even among ancient civilizations. They used medical cannabis as an anesthetic, to treat wounds and sores, and to make drinks like bhang (traditional drink in India) that helped to quicken digestion, clear phlegm, sharpen the appetite, and had other uses as well.

The effects of weed are experienced as a result of the endocannabinoid system (EC) in the human body. The EC is made up of endocannabinoid receptors both in the brain and all over the body that regulate the metabolism, maintain homeostasis, and affect the memory, appetite, and other functions inside the body. These receptors are also the ones that react with the cannabinoids in cannabis and produce the physical and psychoactive effects on users.

Now, let’s go over how the use of marijuana can help with various medical conditions, the possible side effects, as well as which US states have legalized the use of medical marijuana under the federal government.

What Is Medical Marijuana?

The marijuana plants contain over 400 chemical entities. Among them are cannabinoids, terpenes, and other chemical compounds that are used for their medicinal and recreational properties. The most popular ones are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the main cannabinoids used for medical purposes. 

Medical marijuana refers to the use of the Cannabis Sativa plant or its chemicals in order to treat some diseases or medical conditions and it’s prescribed by a licensed physician. Because the medical benefits of using cannabis sometimes outweigh the side effects, marijuana use has significantly increased in recent years.

Where Is Medical Cannabis Legal in the US?

A lot of clinical trials have been done on the health effects of marijuana on users. After numerous studies on the effects of CBD, the 2018 Farm Bill legalized CBD derived from the hemp plant that contains less than 0.3% THC in all 50 states. 

On the other hand, the medical use of marijuana has been legalized by the federal government in the following US countries:

  • Alaska;
  • Arizona;
  • Arkansas;
  • California;
  • Colorado;
  • Connecticut;
  • Delaware;
  • District of Columbia;
  • Florida;
  • Hawaii;
  • Illinois;
  • Louisiana;
  • Maine;
  • Maryland;
  • Massachusetts;
  • Michigan;
  • Minnesota;
  • Mississippi;
  • Missouri;
  • Montana;
  • Nevada;
  • New Hampshire;
  • New Jersey;
  • New Mexico;
  • New York;
  • North Dakota;
  • Ohio;
  • Oklahoma;
  • Oregon;
  • Pennsylvania;
  • Rhode Island;
  • Utah;
  • Vermont;
  • Washington;
  • West Virginia.

States allowing legal recreational use include: Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont, and Washington.

States that allow restricted use only include: Alabama, Georgia, Idaho, Iowa, Kentucky, Mississippi, Missouri, North Carolina, South Carolina, Tennessee, Texas, Virginia, Wisconsin, and Wyoming. Each state has specific rules and regulations when it comes to the use of medical marijuana, however, the FDA hasn’t approved it on a federal level. 

What Does Medical Cannabis Treat?

While some people are using marijuana as an opioid alternative, especially patients with cancer diagnoses, medical cannabis can help treat a number of medical conditions such as the following:

  • Alzheimer’s disease;          
  • Appetite loss;
  • Cancer; 
  • Crohn’s disease;                 
  • Diseases affecting the immune system like HIV/AIDS or Multiple Sclerosis (MS);
  • Eating disorders such as anorexia;
  • Epilepsy;          
  • Glaucoma;          
  • Mental health conditions such as schizophrenia and posttraumatic stress disorder (PTSD);
  • Multiple sclerosis;         
  • Muscle spasms and spasticity (tight or stiff muscles);        
  • Nausea;          
  • Chronic pain;          
  • Seizures;   
  • Wasting syndrome or extreme weight loss (cachexia). (National Academies of Sciences, Engineering, and Medicine, Washington DC, 2017)

How Does It Help?

Our endocannabinoid system, which is made of cannabinoid receptors, endogenous cannabinoids, and the enzymes that degrade the cannabinoids, is responsible for maintaining the balance in our body. It regulates metabolism, appetite, memory, movement, intracellular communication, and other functions.

Cannabis affects the endocannabinoid system via the cannabinoids (active chemicals) that affect the CB1 and CB2 receptors in the body. Consequently, cannabis can affect various pain syndromes and seizures that affect these functions. 

Cannabinoids might help to:

  • Reduce anxiety;      
  • Reduce inflammation;
  • Relieve pain; 
  • Reduce nausea and vomiting (in patients undergoing chemotherapy);         
  • Kill cancer cells and slow tumor growth;        
  • Relax tight muscles (as a result of MS);    
  • Stimulate appetite and improve weight gain (in patients with eating disorders, patients that have cancer and AIDS). 

Is Medical Marijuana Approved by the FDA?

When it comes to medical marijuana and its legalization on the federal level, that hasn’t happened yet. Only states that have legalized the use of medical cannabis can use it as a treatment option for medical conditions.

The U.S. food and drug administration, responsible for the regulation of medicine in the US, has approved only one cannabis-derived product that contains cannabidiol – Epidiolex. It was approved for the treatment of two severe forms of epilepsy (Lennox-Gastaut syndrome and Dravet syndrome).

Following the approval of Epidiolex, two more man-made cannabinoid medicines were approved as a treatment for nausea and vomiting as a side effect of chemotherapy. The first one is Dronabinol (also known as Marinol and Syndros) and Nabilone (also known as Cesamet).

How Do Medical Patients Consume Medical Marijuana?

There are several ways you can consume medical marijuana and each method takes a different amount of time before you feel the effects in your body:

  • Inhalation (you can smoke medical marijuana in a joint, blunt, vape pen, or use a bong);
  • Ingestion (medical cannabis can also be consumed in the form of cannabis edibles like candies, cookies, brownies, gummies);
  • Sublingually (you can take medical cannabis by putting a few drops of liquid concentrate under your tongue);
  • Topical application (medical marijuana can be applied on the skin to treat localized pain in the form of cannabis-infused lotions, balms, and oils that are absorbed through the skin).

The Side Effects of Medical Marijuana

Similar to consuming other drugs and opiates, marijuana can also produce some unwanted side effects in users, although they’re less severe as opposed to side effects from other drugs. The most common ones include:

  • Red eyes;
  • Dry mouth (cottonmouth);
  • Depression;       
  • Dizziness;          
  • Increased heartbeat;
  • Hallucinations;          
  • Lower blood pressure.

Cannabis consumption can also affect your coordination and judgment which is why you should refrain from driving and operating heavy machinery after consuming it. Moreover, long-term cannabis use can be a trigger for schizophrenia or psychosis in patients who are at high risk for these conditions.

Cannabis is also considered a “gateway drug” to using other drugs by The National Institute on Drug Abuse. They view cannabis as highly addictive, which means that the more you use it, the more addicted you become. 

Long-term marijuana use can be especially harmful to young adults since it can lead to neural alterations and a reduction of OFC gray matter volume. Finally, similar to tobacco, scientists are concerned that marijuana smoke could affect lung health and harm the lungs.

Final Thoughts on Medical Marijuana

The potential side effects of cannabis are often put to the side when medical patients need medical marijuana as part of their treatment options. In states where medical cannabis is legal, potential patients need to apply for a medical marijuana ID in order to become eligible to purchase it. A doctor will determine whether your condition qualifies for medical marijuana use, after which you’ll be issued your card. After acquiring your card, you can purchase medical marijuana at a licensed medical marijuana dispensary.

Additional Sources

National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Population Health and Public Health Practice; Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington (DC): National Academies Press (US); 2017 Jan 12. 4, Therapeutic Effects of Cannabis and Cannabinoids. Available from: https://www.ncbi.nlm.nih.gov/books/NBK425767/ 

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.