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Uses of Medical Marijuana

April 10, 2025

Medical marijuana is an issue that has drawn significant debate. As of 2025, it has been legalized for medical use in 39 states (and also for recreational use in 24). Cannabis is becoming more present in the medical landscape and corporations have begun developing and selling a wide variety of products incorporating it. A few cannabinoids have received FDA approval. This relaxation of previous bans has benefitted many, but it has also opened up cannabis to for-profit industries and unethical marketing.

Marijuana is routinely marketed to the public for a wide variety of purposes. It is sold as medicine, but also food, drinks, soap, makeup, and a huge number of other products. Companies that sell medical and recreational marijuana often make sensational claims about how much it can improve one’s health, downplay or ignore any risks that come with their products, then slip in a fine-print statement that they “cannot guarantee the accuracy” of any of the information that they themselves promote.

So what conditions does cannabis actually treat, and what are its risks and benefits?

Chronic Pain

A number of studies have supported the theory that cannabis is effective at treating chronic pain in adults. An important limitation to this statement is that most studies on the topic were conducted with nabiximol, a marijuana extract that is only available as a medication outside the United States. The studies that came from the US investigated marijuana that was instead vaporized or smoked. Nonetheless, the NIH recommended in 2017 that more research be done to investigate the effects of medical marijuana on chronic pain, especially with regard to different forms of cannabis and methods of administration.

Nausea and Vomiting Caused by Chemotherapy

When cancer patients go through chemotherapy, they often experience the unpleasant side effects of nausea and vomiting. To counteract this, they are often prescribed antiemetic drugs, which prevent those symptoms. So far, two THC-based medications have been approved by the FDA: nabilone and dronabinol. They were both found in clinical trials to have greater effects than placebos, and are considered to be as effective as medications that do not include cannabis products. Nabilone and dronabinol are sometimes given to patients who do not experience improvement after trying other antiemetics.

Spasticity?

There have been many studies that have examined the possibility that medical marijuana can alleviate spasticity, a symptom of some neurological conditions. Spasticity involves muscle stiffness and a loss of control over one’s movements. Cannabis extracts, nabiximols, and THC have all been tested as potential treatments. However, the results of these studies are often divided in a curious way. When people with Multiple Sclerosis (MS) are treated with cannabis, they report moderate but significant improvements in their symptoms. At the same time, when spasticity is measured by a doctor, there is no consistent effect reported. As with chronic pain, more research is needed on the link between medical marijuana and spasticity symptoms.

Sleep Disorders?

Cannabis has also been studied for a potential effect on a number of sleep issues with a wide variety of causes. The NIH stated in 2017 that there was “moderate evidence” that nabiximols could reduce sleep disturbances that were symptoms of sleep apnea, fibromyalgia, chronic pain, and Multiple Sclerosis. However, these effects were only observed in the short term. Again, more research is necessary before we can fully conclude that medical marijuana can treat sleep problems.

Risks

  • Side effects: As with most medications, medical marijuana can have side effects, which most often are minor, such as drowsiness. Use of marijuana as medicine can also occasionally cause symptoms similar to those of recreational use (the “high”) when taken at higher doses.
  • Addiction: It is possible to develop an addiction to marijuana. Among people who use marijuana, the proportion who become dependent on it is roughly 9-10%; this figure is considerably lower than addiction rates for many other drugs, both legal (15% for alcohol, 23% for opioids, and 32% for nicotine) and illegal (17% for cocaine and 23% for heroin). In addition, marijuana addiction tends to develop gradually, and the risk decreases as the user ages. After age 25, a person’s risk of becoming dependent on marijuana is roughly 0%.
  • Effects on physical, cognitive, and mental health: A number of other concerns have been raised about marijuana/cannabis use. Some users of medical marijuana consume it via smoking, which may increase their risk for lung cancer. It is known that recreational consumption of marijuana can cause detrimental cognitive effects such as learning loss, and it is unclear whether medical use has the same effects or not. Finally, some studies have found associations between marijuana use and the development of mental illnesses, especially schizophrenia and psychotic symptoms. However, an association is different from a causal effect, and the most dramatic links tend to be in people who already displayed symptoms or who were considered to have a higher risk of mental illness than the average person. All of these effects require more research to determine the likelihood of these risks to medical marijuana users, who generally use smaller doses and different methods of consumption than recreational marijuana users.

A Marijuana Myth – The “Gateway Drug”

One idea that historically has been brought up frequently in discussions of the risks of marijuana is the statement that marijuana is a “gateway drug.” The Marijuana Gateway Hypothesis holds that marijuana use increases a person’s risk for using more dangerous drugs later on. If true, this would be a significant risk for recreational users and likely for medical users as well. However, research on this topic is often performed without control groups and does not always find statistically significant results. Even studies that do produce significant results have found support only for correlations and temporal connections (one event happening after another) between marijuana use and later hard drug use. This leaves open the possibility that there are other variables, called third variables, that influence both a person’s marijuana use and hard drug use. Third variables can be characteristics of the people themselves, or aspects of the environment they live in. A list of possible third variables includes: peer groups and social encouragement/pressure to use particular substances, level of engagement with school, deviant behaviors, thrill seeking, problems with behavioral and emotional regulation, level of self-control, genetics, and age at first use. Given that there are so many alternate explanations for hard drug use other than marijuana use, it is unlikely that the Marijuana Gateway Hypothesis is accurate.

Conclusions

The subject of medical marijuana has been heavily distorted and clouded by misinformation and marketing. To clear the confusion, accurate information needs to be provided to consumers regarding what conditions can be treated with cannabis and the potential risks and benefits of using cannabis-related products. In addition, people should be aware of the limits of our current knowledge. Many aspects of medical marijuana have not been studied closely, and we are acting on limited information that may change as marijuana is researched more widely in a clinical setting. There may come a day when we will know everything there is to know about cannabis treatments and understand exactly how useful they are for every imaginable human condition, and these facts will be common knowledge available to all. Until then, it’s best to do some fact-checking when faced with exaggerated claims or a decision about your health.

 

Resources:

Ayers, John W., et al. “The Need for Federal Regulation of Marijuana Marketing.” JAMA, vol.         321, no. 22, 11 June 2019, pp. 2163–2164, jamanetwork.com/journals/jama/article-         abstract/2734209, https://doi.org/10.1001/jama.2019.4432. Accessed 26 June 2020.

Bostwick, J. Michael. “Blurred Boundaries: The Therapeutics and Politics of Medical      Marijuana.” Mayo Clinic Proceedings, vol. 87, no. 2, Feb. 2012, pp. 172–186,             www.mayoclinicproceedings.org/article/S0025-6196(11)00021-8/fulltext,             https://doi.org/10.1016/j.mayocp.2011.10.003.

Cohen, Peter J. “Medical Marijuana: The Conflict between Scientific Evidence and Political            Ideology. Part One of Two.” Journal of Pain & Palliative Care Pharmacotherapy, vol.         23, no. 1, Jan. 2009, pp. 4–25, https://doi.org/10.1080/15360280902727973.

Jorgensen, Cody, and Jessica Wells. “Is Marijuana Really a Gateway Drug? A Nationally     Representative Test of the Marijuana Gateway Hypothesis Using a Propensity Score             Matching Design.” Journal of Experimental Criminology, vol. 18, 6 Apr. 2021,             https://doi.org/10.1007/s11292-021-09464-z.

National Library of Medicine. “Therapeutic Effects of Cannabis and Cannabinoids.” Nih.gov,         National Academies Press (US), 12 Jan. 2017,   www.ncbi.nlm.nih.gov/books/NBK425767/.

Pratt, Misty, et al. “Benefits and Harms of Medical Cannabis: A Scoping Review of Systematic           Reviews.” Systematic Reviews, vol. 8, no. 1, Dec. 2019, pp. 1–35,      https://doi.org/10.1186/s13643-019-1243-x.

Wikipedia Contributors. “Legality of Cannabis by U.S. Jurisdiction.” Wikipedia, Wikimedia Foundation, 19 March 2025,      en.wikipedia.org/wiki/Legality_of_cannabis_by_U.S._jurisdiction.

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.