Medical Marijuana for Cancer Side Effects: Benefits & Risks

Cancer treatment is known to be associated with side effects like pain (through nerve damage), nausea, vomiting, loss of appetite, and weight loss. These effects make cancer treatment very challenging, and many people are seeking adjunct treatments for cancer side effects.

Medical marijuana is one option that has gained significant attention in the treatment of cancer-related side effects. Its use in the treatment of cancer side effects has become widely discussed in countries like Canada, France, and the United States, and many patients and caregivers are now asking about its effectiveness and safety.^[1]Ramírez, T. (2019). Thematic debate on cannabis and cannabinoids: Contribution. United Nations Office on Drugs and Crime.

Though not recommended as a first-line treatment for cancer-related side effects, medical marijuana may help provide significant relief to cancer treatment side effects like pain and chemotherapy-induced nausea and vomiting.^[2]Ontario Health. (n.d.). Cannabis and cancer. https://ontariohealth.ca/content/dam/ontariohealth/documents/cannabis-cancer.pdf However, it is good to have a good understanding of its potential benefits and risks before considering its use in the treatment of cancer side effects

In this article, you will learn how medical marijuana may help with cancer side effects, its potential benefits and risks, and what to consider before using it.

Understanding Medical Marijuana

Medical marijuana refers to the use of the whole, unprocessed Cannabis sativa plant or its extract to treat symptoms of chronic illness or cancer. In contrast to recreational use of Cannabis, medical marijuana refers to the use of Cannabis products or its extract as a medicine for eligible conditions, but it is currently not legal in all countries.

Cannabis, also known as marijuana, Indian hemp, weed, etc., produces its recreational and medical effects through its biologically active constituents known as cannabinoids, particularly CBD (Cannabidiol) and THC (Tetrahydrocannabinol). THC is the constituent responsible for the psychoactive “high” associated with cannabis use, but CBD does not produce this euphoric effect, and the latter is more commonly associated with the medical benefits of marijuana.

Medical marijuana may contain different proportions of THC and CBD, depending on the medical effect desired and the condition being treated. For example, some formulations contain CBD:THC ratios of 0:1, 1:0, 1:1, 2-4:1, and >10:1.

While THC has more cancer-related benefits, the CBD constituent provides better anti-anxiety and anti-seizure effects. In addition, formulations containing both CBD and THC in varying ratios are often preferred to pure THC formulations because CBD helps to reduce the adverse psychoactive side effects of THC.

How Medical Marijuana Helps Cancer Treatment Side Effects

Cancer chemotherapy is often associated with side effects like cancer pain, nausea, vomiting, loss of appetite and weight loss, and poor sleep. These distressing symptoms can be so severe that as many as 20% of patients discontinue treatment. However, research shows the promising benefits of medical marijuana in the management of these side effects as follows.^[3]Parker, L. A., Rock, E. M., & Limebeer, C. L. (2011). Regulation of nausea and vomiting by cannabinoids. British journal of pharmacology, 163(7), 1411–1422. … Continue reading

1. Cancer pain relief

All forms of cancer treatment (chemotherapy, radiotherapy, immunotherapy, or hormonal therapy) cause pain as a common side effect. These drugs trigger inflammation, causing joint pain, joint stiffness, joint swelling, muscle soreness, and tingling or painful neuropathy of the fingers and toes.^[4]MD Anderson Cancer Center. (n.d.). Cancer treatment side effect: Joint pain. https://www.mdanderson.org/cancerwise/cancer-treatment-side-effect–joint-pain.h00-159778812.html

Medical marijuana may help in the treatment of cancer pain, particularly when conventional pain medications do not provide adequate relief at usual doses. THC activates cannabinoid receptors (CB1 receptors) in the brain and central nervous system to directly modulate pain perception.

On the other hand, CBD does not directly relieve pain like THC, but it helps to reduce inflammation and anxiety, and reduces the psychogenic side effects of THC. Because of this, research has suggested that medical marijuana products with an equal balance of THC and CBD are particularly more effective and better tolerated for cancer pain treatment.^[5]BMJ Group. (2022). Medicinal cannabis can safely relieve cancer pain and curb total meds use. https://bmjgroup.com/medicinal-cannabis-can-safely-relieve-cancer-pain-and-curb-total-meds-use/

2. Chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) is a common side effect affecting 40% of cancer patients on chemotherapy. They are considered the most-feared adverse effects associated with cancer chemotherapy. Chemotherapeutic drugs cause nausea and vomiting (emesis) by activating neurotransmitter receptors in the area postrema of the brain or by stimulating vagal afferents near the enterochromaffin cells in the intestine.^[6]Gupta, K., Walton, R., & Kataria, S. (2020). Chemotherapy-Induced Nausea and Vomiting: Pathogenesis, Recommendations, and New Trends. Cancer Treatment and Research Communications, 26, 100278. … Continue reading

The THC component of medical marijuana is also useful in the treatment of CINV, particularly when conventional antiemetic drugs do not produce desired results. Early clinical studies show that cannabinoid drugs like nabilone, dronabinol, and similar drugs have comparable effects to conventional dopamine antagonists such as prochloperazine.^[7]Parker, L. A., Rock, E. M., & Limebeer, C. L. (2011). Regulation of nausea and vomiting by cannabinoids. British journal of pharmacology. ibid.

Patients who do not respond to the therapeutic effect of anti-dopaminergic antiemetic drugs would benefit from medical marijuana because it acts on the endocannabinoid system. In addition, the latter addresses several symptoms (nausea, vomiting, pain, and loss of appetite) at once, which is a major reason some clinicians consider them.

3. Loss of appetite and weight loss

While nausea and vomiting can lead to loss of appetite and weight loss in cancer patients receiving chemotherapy, cancer chemotherapy can directly affect appetite by altering taste (metallic taste) and smell, reducing saliva, and causing early fullness. Chemotherapy can also produce chemical changes (cytokines) from dying cancer cells, which suppress hunger, leading to weight loss.^[8]Cancer Research UK. (2023, September 13). Taste changes and loss of appetite. https://www.cancerresearchuk.org/about-cancer/coping/physically/diet-problems/types/taste-changes-and-loss-of-appetite

Accounts of cancer patients and caregivers on a Mayo Clinic forum confirm the effectiveness of medical marijuana for loss of appetite during chemotherapy. THC is associated with increased appetite and weight gain, while CBD has been shown to decrease appetite.

Thus, THC-predominant medical marijuana combinations are effective for boosting appetite and improving body weight in cancer patients receiving chemotherapy.

4. Sleep and overall quality of life

Studies show that almost 80% of cancer patients will complain of disturbed sleep at some point during treatment.^[9]MD Anderson Cancer Center. (2013, September 6). Sleep, cancer, and cancer treatment: Understanding the link. … Continue reading Methotrexate, a commonly used chemotherapeutic drug for cancer, disrupts sleep by targeting the central nervous system (CNS) through unclear mechanisms, while hormonal cancer therapy has been shown to cause sleep disturbance in up to 60% of cancer patients on treatment.^[10]Mong J. A. (2025). Chemotherapy’s hidden side effect: sleepless nights without cancer. Sleep, 48(7), zsaf110. https://doi.org/10.1093/sleep/zsaf110

Sleep is fundamental to normal functioning and quality of life. Thus, cancer and/or its treatment can significantly affect the quality of life through sleep disruption.

THC-dominant marijuana strains can be used to induce sedation, while CBD is effective for anxiety reduction in patients on cancer treatment.

Benefits of Medical Marijuana in Cancer Care

Medical marijuana may provide several benefits in supportive cancer care, particularly in the management of treatment-related side effects. While there is insufficient evidence to show that it cures cancer, it offers the following benefits to cancer patients receiving treatment.

1. Relief of multiple symptoms: Due to its ability to provide relief for several symptoms, medical marijuana may help prevent polypharmacy and enhance drug adherence in cancer patients.

2. Alternative options to standard treatments: Medical marijuana can be used as an alternative treatment option, particularly when conventional treatments fail to address cancer-related side effects. THC and CBD interact with the endocannabinoid receptor system, which can provide therapeutic effects when there is no response from opioid receptor medications.

3. Possible reduction of the number of concomitant drug use: There is evidence that medical marijuana produces several results at a time, thus reducing the number of drugs used in the treatment of cancer treatment side effects.

4. Stimulation of appetite and weight support: While cancer and its treatment can lead to poor appetite and weight loss, THC-containing medical marijuana may help stimulate appetite and reduce weight loss.

5. Improved quality of life: By helping in the management of symptoms such as pain, nausea, and vomiting, medical marijuana may contribute to the quality of life among cancer patients receiving chemotherapy.

Risks and Side Effects of Medical Marijuana

Medical marijuana can come in different formulations depending on the condition being treated. Here are some of the risks and side effects to know before considering its use. It is important to use medical marijuana under medical supervision and choose the appropriate THC:CBD combination to reduce these side effects.

1. It can cause dizziness and drowsiness
2. Confusion
3. Dry mouth
4. Increased heart rate
5. Impaired memory and cognitive function
6. Euphoria
7. Anxiety
8. Fatigue
9. Headache
10. Increased appetite
11. Possible dependency or addiction
12. Respiratory problems

How To Reduce Side Effects of Medical Marijuana

The above side effects of medical marijuana can impact the patient’s health and quality of life. Here are some noteworthy precautions to help reduce marijuana side effects when used as a treatment for cancer side effects.

1. Use under medical supervision: Ensure you discuss the response, effects, and adverse effects with your oncologist when using medical marijuana for treating treatment-related cancer side effects.
2. Start with a low dose and increase gradually: It is important to start at the lowest effective dose, especially if you have never used marijuana before. This is necessary for reducing its side effects and also preventing cannabis dependence.
3. Choose formulations with an appropriate THC:CBD ratio. Medical marijuana products with a balanced CBD:THC ratio are most recommended for new users. This is because CBD helps to cancel out the psychoactive effects of THC in the formulation.
4. Avoid self-medication: Prioritize a licensed oncology center over an OTC marijuana purchase. Self-medicating without any professional guidance can predispose one to recreational, addictive marijuana use in the course of cancer treatment.
5. Monitor for side effects: Look out for marijuana side effects like dizziness, fatigue, impaired alertness, and mood changes. If any severe or persistent symptoms occur, it is important to notify your doctor immediately.

Can Medical Marijuana Cure Cancer?

There is currently not enough evidence to support that medical marijuana or any form of cannabis can cure cancer, but it has shown remarkable promise in the management of cancer symptoms or treatment side effects, as discussed above. Marijuana does not have any direct effect on cancer growth and proliferation, but THC or CBD can interact with certain receptors to modulate the side effects of cancer or its treatment.

Thus, claims that CBD oil has been successfully used to cure lung cancer are unfounded and misleading.

Forms in Which Medical Marijuana is Used

Medical marijuana may be used in the following preparations:

• Oils
• Oral preparations
• Sprays (e.g., nabiximols)

Who Can Use Medical Marijuana

Medical marijuana for cancer side effects may be useful to the following categories of individuals:

• Patients with uncontrolled cancer side effects
• Patients not responding to standard treatment of treatment-related side effects
• Patients experiencing multiple concomitant symptoms
• People who have access to professionals who are specialized in marijuana-based treatments in areas where this is considered permissible by law.

Other Medical Uses of Marijuana

In addition to its use in the management of cancer side effects, medical marijuana has been studied for use in other conditions like epilepsy/seizure disorders, chronic pain, anxiety disorders, sleep problems, and multiple sclerosis. However, its use should be guided by professional medical advice and the legal regulations surrounding marijuana use in the area.

Who Should Avoid Medical Marijuana

While medical marijuana could be beneficial for the treatment of cancer side effects and other above-listed medical conditions, its use is not recommended for the following category of individuals.

1. Pregnant and lactating women: THC can cross the placenta into the fetus to affect the fetal brain, causing problems with attention, memory, and problem-solving. It can also increase the risk of stillbirth, premature delivery, and low birth weight. In lactating mothers, THC can be secreted into breastmilk, also affecting infant brain development.
2. Marijuana may worsen the clinical condition in patients with psychosis.
3. People with heart disease should avoid marijuana in any form. Studies have demonstrated clear associations between marijuana use and increased risk of heart attack, even in apparently healthy patients.

Is Medical Marijuana Legal?

Legal considerations surrounding the use of marijuana for medical reasons vary from country to country. While some countries consider all forms of marijuana illegal, others apply regulatory control to its use.

In the United States, federal laws legalize hemp-derived cannabinoids because they contain less than 0.3% THC. Marijuana-derived cannabinoids have higher THC concentrations and are classified as illegal under the Controlled Substances Act. There may also be state-specific regulations that may or may not differ from federal regulations surrounding marijuana use.

Frequently Asked Questions

Conclusion

Medical marijuana is gradually gaining attention in public conversations concerning its use in the management of cancer side effects. This post explored some important medical uses of marijuana for cancer treatment, its side effects, and precautions for use.

This topic raises several questions, many of which are outside the scope of this article. But let me know in the comments section if you have any questions related to medical marijuana in the treatment of cancer side effects and other medical conditions.

This article is for informational purposes only and does not replace professional medical advice. Always consult a qualified healthcare provider before using medical marijuana.