Medical cannabis and chronic pain: the use of the plant to reduce symptoms

Posted on 10/06/22 | Updated 06/10/22 Reading: 11 minutes


It is estimated that at least 37% of the Brazilian population experience chronic painaccording to the Brazilian Society for the Study of Pain (SBED). The classification takes into account pain that persists or recurs for more than three months and the causes are most often related to chronic diseases, such as osteodiscodegenerative diseases, neurological disorders and cancer. Treatment is usually carried out with drugs, physiotherapy and psychotherapy, but other adjuvants often need to be considered. The use of Medical Cannabis in the management of chronic pain has been widely studied and there are several benefits of cannabinoid derivatives for this condition. 


What is the evidence for the use of Cannabis in chronic pain? 

First of all, it is important to know more about the Endocannabinoid System. SE is a vital regulatory system, present in humans and all vertebrate animals, which is involved in almost all of our physiological and pathological processes. 

The interaction of endocannabinoid receptors with their main ligands regulates and modulates stress, emotions, digestion, cardiovascular functions, the immune system, inflammatory processes and also pain.

This interaction can be stimulated by chemical compounds present in Cannabisthe plant’s phytocannabinoids and terpenes can help balance the functional tone of this system. Therefore, medicinal cannabis can be an important ally in the management of chronic pain. 

A review published in July 2021 concludes that there is substantial evidence from preclinical studies that cannabinoids hold great promise for the development of analgesic drugs. The authors also point out that further studies are needed to better understand the pharmacology and therapeutic potential of other phytocannabinoids, in addition to the main THC and CBD — and how other plant chemical elements interact with both in analgesia. 

>> Check at Cannabinoids, the endocannabinoid system, and pain: a review of preclinical studies.


This study from 2020, properly depicts such potential. The authors evaluated the use of medicinal cannabis in patients with chronic pain who regularly take opioids. For at least 3 months, more than 500 patients have used cannabis in combination with previously prescribed opioid drugs to treat chronic pain. In relation to opioids: 


  • 40.4% of respondents interrupted use;
  • 45.2% reported some decrease to the use;
  • 3.3% did not manage any changes to the substance use;
  • 1.1% increased ingestion. 


Most reported improvement in functional capacity (80%) and quality of life (87%). Nearly half (48.2%) described a 40 to 100% reduction in pain.

>> Read more in: A Survey on the Effect That Medical Cannabis Has on Prescription Opioid Medication Usage for the Treatment of Chronic Pain at Three Medical Cannabis Practice Sites

Results from an observational and longitudinal study , also from 2021, point out that exposure to THC is related to pain improvement, while CBD is associated with an improvement in mood — consequently, decreasing unpleasant sensations associated with pain. Aspects such as pain, clinical status, sleep pattern, quality of life and use of conventional drugs in patients with chronic pain who also used medicinal cannabis in their treatment were evaluated.

>> See No pain, all gain? Interim analyses from a longitudinal, observational study examining the impact of medical cannabis treatment on chronic pain and related symptoms


Cannabis and migraine

Nine out of 10 migraine patients can get pain relief by inhaling cannabis. The finding is from a study in which researchers followed the effects of the inhaled plant in 699 people with migraine, for 32 months. 94% of patients reported symptom relief within two hours after inhalation. Cannabis varieties with THC content equal to or greater than 10% were found to be more effective in pain relief. 

>> Learn more: Alleviative effects of Cannabis flower on migraine and headache

Other studies also demonstrate the promising potential of using cannabinoid derivatives in migraine patients. Preliminary results from a study carried out in 2020 indicate that 86% of patients who suffered from headaches reported improvement in their symptoms after using CBD oil in a 30-day treatment.

Using data from a medical cannabis application used by patients to track symptoms before and after using the plant, researchers reported that there are significant reductions in signs of migraine and headaches after using the plant. Inhaled cannabis decreased pain intensity associated with migraine by approximately 50%.

>> Read in: Short- and Long-Term Effects of Cannabis on Headache and Migraine


Cannabis and fibromyalgia 

Israeli researchers studied the association between cannabis and chronic pain in patients at two medical centers specializing in the treatment of fibromyalgia. After 10 to 11 months of treatment with cannabis, 100% dos respondentes tiveram melhora nos sintomas da doença em todos os quesitos do questionário, with better results in those related to pain. At least 50% of them reported having stopped using other drugs after starting medical cannabis. Adverse effects were reported by 30% of patients, but all were considered mild—headaches, nausea, excessive hunger, dry mouth, and drowsiness.

>> Refer to the study: Medical Cannabis for the Treatment of Fibromyalgia

Cannabis extracts with a higher concentration of THC can reduce pain and considerably improve the quality of life of people with fibromyalgia. This is what a controlled, randomized, double-blind clinical study from October 2020 proves. The research was conducted by physicians from the Federal University of Santa Catarina (UFSC). Within 8 weeks of treatment, the group using medical cannabis had a decrease in fibromyalgia severity from 75 to 30while patients receiving placebo recorded a decrease from 70 to 61—a scale of 0 to 100 on the andscore Fibromyalgia Impact Questionnaire (FIQ) (FIQ)

An interesting point of the study is that it used a “handmade preparation”. Thus, the authors also conclude that phytocannabinoids, in addition to being efficient, can be a low-cost therapy.

>> Refer to the study Ingestion of a THC-Rich Cannabis Oil in People with Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.


Cannabis and neuropathic pain 

Researchers estimate that the neuropathic component may be present in about 35% of all pain syndromes. The patient has a tingling, burning sensation or hypersensitivity to touch or cold.

In pre-clinical studies with rodents, it was observed that activation of endocannabinoid receptors was able to reduce chronic neuropathic inflammatory pain. Other research in animal models showed that, after treatment with CBD for 7 days, there was normalization of serotonergic neurotransmission (5-HT), reduction of mechanical allodynia and reduction of anxiety behavior.

>> Learn more at A Review of Scientific Evidence for THC:CBD Oromucosal Spray (Nabiximols) in the Management of Chronic Pain

In this randomized, double-blind clinical trial, when administering treatment with THC and CBD for 4 weeks in 125 patients with neuropathic pain of peripheral origin, researchers noticed a significant reduction in the pain score. They also observed significant improvements in other parameters, such as neuropathic pain scores (Neuropathic Pain Score), Pain Disability Index and patient’s global impression of change (Patient’s Global Impression of Change). Adverse effects reported were mainly sedative or gastrointestinal.


>> See: Sativex successfully treats neuropathic pain characterised by allodynia: a randomised, double-blind, placebo-controlled clinical trial

A group consisting of pain specialists, psychiatrists, scientists and patients came together to assess the relationship between the benefit and safety of 12 pharmacological treatments for the management of chronic neuropathic pain, including cannabis-based medications. The result, published in 2021, indicates that cannabis-based medications achieved the highest score, ahead of medications often prescribed to these patients such as duloxetine, gabapentinoids, amitriptyline, tramadol, ibuprofen, among others. 

>> Read the whole study: A Multicriteria Decision Analysis Comparing Pharmacotherapy for Chronic Neuropathic Pain, Including Cannabinoids and Cannabis-Based Medical Products


Cancer Pain and Cannabis

In the analysis “Should oncologists recommend cannabis?”the author highlights the recommendation to prescribe a drug based on cannabis in the refractoriness of the use of other drugs forpatients who developed peripheral neuropathy induced by chemotherapy. 

It is noteworthy that medicinal cannabis has a synergy of action with opioids, normally prescribed to control pain associated with cancer. Most patients with chronic pain, who regularly use opioids and start treatment with plant derivatives, manage to prevent the development of tolerance to opioids, avoiding the progressive increase in the dosage of these drugs.

>> Read more: Should Oncologists Recommend Cannabis?


Além da dor crônica, outros sintomas são relatados com frequência pelos pacientes de diversos tipos de câncer. São eles a fatigueto insônia and the inapetência. Também não são raros os quadros de anxiety, depression, náuseas and vômitos, consequências naturais dos protocolos de radio e quimioterapia. 

All these symptoms associated with cancer and the side effects resulting from its treatment can be improved with the use of medicinal cannabis as a therapeutic adjuvant in the oncological context. This is demonstrated by the promising results of research that reinforce the plant’s potential in this context.

>> See Opportunities for cannabis in supportive care in cancer, published in 2019.


Want more data? How about the results of this study published in 2018, which evaluated a group of 2,970 cancer patients treated with medical cannabis between 2015 and 2017? After six months of follow-up with cannabis therapy, patients responded as follows:

  • 95.9% of them reported an overall improvement in their condition
  • 3.7% did not report any changes and 
  • 0.3% reported worsening of their medical condition.

To get deeper into the potential of cannabinoid derivatives in the cancer context, read our article on Cannabis as adjuvant therapy in cancer patients


Pelvic Pain and Cannabis

The analgesic and anti-inflammatory properties of phytocannabinoids also appear as a safe and effective alternative for relieving frequent and intense pain, prevalent in the pelvic region. Cannabis-based medications may be beneficial in the treatment of chronic pelvic pain, especially when associated with endometriosis. To read more about this topic, check out our post on Medical Cannabis for Women. 

A study from 2020 showed that 20% of patients who participated in the survey reported using the plant to alleviate chronic pelvic pain, especially symptoms of pain, muscle spasms, irritability, anxiety and depression symptoms, sleep disorder and reduced libido.

>> See Use of Cannabis for Self-Management of Chronic Pelvic Pain

are just some of the existing evidence regarding the therapeutic potential of cannabis in the management of chronic pain. In 2017, The Health Effects of Cannabis and Cannabinoids by the US National Academy of Sciences, Engineering and Medicine concluded that there is substantial conclusive scientific evidence for the use of cannabinoids in chronic pain.


If you want to learn more about the subject and incorporate this valuable therapeutic tool into your practice, check out the WeCann Academy’s CInternational Certification in Endocannabinoid Medicine. 



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Gruber SA, Smith RT, Dahlgren MK, Lambros AM, Sagar KA. No pain, all gain? Interim analyses from a longitudinal, observational study examining the impact of medical cannabis treatment on chronic pain and related symptoms. Exp Clin Psychopharmacol. 2021;29(2):147-156. doi:10.1037/pha0000435

Habib G, Artul S. Medical Cannabis for the Treatment of Fibromyalgia. J Clin Rheumatol. 2018;24(5):255-258. doi:10.1097/RHU.0000000000000702

HERRINGTON, A.J. Study Finds CBD Is An Effective Treatment For Migraine. Forbes, 2021. Disponível em: <>. Acesso em: 11 de agosto de 2021.

Sarah S. Stith, Jegason P. Diviant, Franco Brockelman, Keenan Keeling, Branden Hall, Storri Lucern, Jacob M. Vigil, Alleviative effects of Cannabis flower on migraine and headache, Journal of Integrative Medicine, Volume 18, Issue 5, 2020, Pages 416-424, ISSN 2095-4964,

Takakuwa KM, Sulak D. A Survey on the Effect That Medical Cannabis Has on Prescription Opioid Medication Usage for the Treatment of Chronic Pain at Three Medical Cannabis Practice Sites. Cureus. 2020;12(12):e11848. Published 2020 Dec 2. doi:10.7759/cureus.11848


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