Using Medical Cannabis to Reduce Harms associated with Long-Term Opioid Use in Chronic Pain

Using Medical Cannabis to Reduce Harms associated with Long-Term Opioid Use in Chronic Pain

Chronic pain – that is not associated with cancer – affects a large proportion of the population, with some estimates suggesting that 25% of adults will experience chronic pain in their lifetimes.

Chronic non-cancer pain (CNCP) can be caused by a variety of factors, including specific past injuries or other conditions such as Multiple Sclerosis or Fibromyalgia. There are a number of challenges to getting on top of chronic pain management, not least the paucity of medications available for chronic pain.

Chronic Pain and Opioid Use

Currently, treatment and symptom management options commonly include the prescription of opioids painkillers, which have been found to have inconsistent efficacy as well as questionable safety profile with a high risk of abuse and overdose. This is now starting to be reflected in the official policies and guidelines of healthcare groups and bodies.

In North America, opioids have become largely associated with chronic abuse in what has become known as the opioid epidemic. The USA and Canada have both declared a public health crisis due to the overuse of both prescription opioids such as morphine, tramadol, and codeine, and illicit opioids, including heroin and fentanyl. Research suggests that a large proportion of opioid abuse in America initially stems from prescriptions provided on an outpatients basis.

As such, safe and effective treatments and symptom management is a key area of medical research.

Medical Cannabis and Chronic Pain

In recent years, medical cannabis and cannabinoid-based medicines are increasingly being considered as a tool to reduce or even cease the use of opioids. Cannabis, also known colloquially as marijuana, has been used medicinally for thousands of years, due to its numerous therapeutic potentials. Furthermore, as medical cannabis becomes more accessible in several countries, chronic pain is quoted as the most common reason for prescription.

A recent study aimed to identify potential strategies in which medical cannabis products could be used to reduce harms associated with opioid use in chronic pain.

Aims and Methods of the study

Given the demonstrated dangers of prolonged opioid use, the United States and Canadian non-cancer pain guidelines have recommended careful reassessment of the risk-benefit ratio for doses greater than 90 mg morphine equivalent dose (MED). Furthermore, in 2017, the Canadian Opioid Guidelines Clinical Tool was created to encourage more careful opioid prescribing and to re-evaluate patients who had been using chronically high MEDs.

The researchers of this study used their clinical experience and available evidence to create a further clinical tool “to serve as a foundational clinical guideline for the initiation of medical cannabis in the management of CNCP patients using chronic opioid therapy.”

Having considered the current evidence and literature in this area, the researchers concluded that there is sufficient evidence to identify a role for cannabis as an adjunct therapy to opioids for the management of chronic pain. Furthermore, this insight prompted the researchers to develop a strategy for the “cautious initiation of cannabis, with a focus on efficacy, safety, titration, and monitoring.”

Following a review of current clinical evidence and clinician experience, the authors of this study propose the following steps be considered relating to the administration of medical cannabis:


First of all, the researchers suggest that the adjunct use of cannabis-based medications should be considered for patients who are not achieving pain management goals, despite consuming more than 90 mg MED per day. Evidence suggests that the risks associated with opioid use at doses higher than this limit are greater than the potential benefits.

The developed guidelines suggest that clinicians should discuss with their patients the risks and benefits of cannabis use, as well as to screen for risk factors for cannabis use disorder and history of personal and family mental health illness when initiating and increasing the dose of tetrahydrocannabinol (THC).

      Starting at a Low Dose

The ingestion of medical cannabis via oral or sublingual routes is recommended for more accurate dosing and to reduce potential respiratory harm associated with smoking plant material. Furthermore, the researchers suggest – particularly for the treatment of inflammatory pain, such as autoimmune conditions or inflammatory arthritis – cannabidiol (CBD)-rich strains should be considered for daytime use.

Preliminary and anecdotal evidence suggests that CBD may have the potential to negate some of the negative effects of other cannabis compounds – namely, the psychoactive compound, THC. Further, some evidence suggests that CBD may also be sufficient for inflammatory pain, without the addition of THC.

The researchers recommend a dose of 5-10 mg of CBD, 1-2 times daily. However, for CNCP patients who have sleeping difficulties, a starting dose of 2.5 mg of THC in the evening is recommended to prevent disruption from side effects.

      Slow Titration until Optimal Dosing

Medical cannabis treatment often requires titration to achieve optimum results. This dose can vary significantly between patients and conditions. Therefore, it is recommended that the dose is increased at low increments to allow patients and doctors to safely monitor for results and side effects associated with the treatment.

The researchers note that it is important to remember that dosage should be titrated until treatment goals are met, and not continued until patients “feel euphoria”. According to the findings of this study, a maximum daily dose of 30 mg of THC is recommended, however, the researchers also note that “if the patient is responding well up to that point, it may be worth continuing to increase until maximal symptom relief, as long as side effects are not outweighing the picture. If there is no response by 30 mg, we do not recommend going higher.”

      Frequent Monitoring

In order to effectively determine the safety and efficacy of medical cannabis treatment, the authors of this study suggest the reassessment of patients at 2-4 week intervals. Furthermore, “this involvement of family members and other allied healthcare providers to monitor for efficacy and side effects” is also strongly recommended. Follow-up intervals may be less frequent once an effective dose is identified, and patient symptoms are improving.

According to the evidence and clinical experience gathered by the researchers, a validated pain tool, as well as questionnaires, such as the Generalised Anxiety Disorder Assessment (GAD-7) are recommended for the documentation of treatment response. At Sapphire Medical Clinics patients can contribute to research on medical cannabis through participation in the Sapphire Access Scheme.

Further, the researchers note, the current CNCP opioid treatment guideline includes the use of urine drug screens to monitor both compliance and risk of addiction. The judicious use of urine drug screens should be a part of the standard of long-term opioid and cannabis treatment monitoring.”

      Optimising Titration

While, in some cases, CBD-dominant products may be efficient to reach satisfactory results, this is not always in the case. The authors of this study note that an additional dose of THC (recommended at 2.5 mg per day in the evening) should be considered where clinically appropriate and titrated as necessary.

For the treatment of intractable neuropathic pain, a balanced 1:1 dose of CBD:THC is recommended due to existing evidence that CBD may be able to mitigate some of the side effects associated with THC administration. The researchers note that, comparable to current opioid initiation guidelines for chronic pain, a successful trial and optimal dose is achieved when “a patient reports ≥30% decrease in pain intensity using a validated tool and/or an improvement in overall function”.

      Discontinue Cannabis Treatment in Case of No Response

As demonstrated in countless clinical trials, there is no “one size fits all” when it comes to medical cannabis treatment. While many patients may experience significant improvement of their symptoms with the help of medicinal cannabis, others may not experience any benefits and, in some cases, may experience worsening symptoms.

As such, the researchers stress that clinicians should monitor their patients frequently to determine the efficacy of medical cannabis treatment. Specifically, it is suggested that, if the patient reaches a total daily dose of more than 30 mg of THC without adequate response, then the option to discontinue medical cannabis treatment should be considered. Based on the collective clinical experience of the researchers, this should be done by tapering the dose of THC by 2.5-5 mg every 2-3 days until discontinuation.

Researcher Conclusions on the Proposed Model

While this proposed model is based on the current evidence and specific clinical experience of the authors of this study, it is noted that there are some limitations to these proposed steps. For example, the researchers concede that it is “not possible to determine which sub-group of opioid-dependent patients will benefit from the addition of medical cannabis”.

As previously stated, and supported by pharmacokinetic studies, people can show a large range of reactions in how different cannabinoids are absorbed and metabolised in different parts of the body. This, alongside a lack of clear consensus in relation to the optimum doses of cannabis medications, makes predictions of individual clinical response particularly difficult.

However, the researchers conclude that “the underlying strategies which create the foundation for this model are based on extant cannabis research, including cannabis-opioid synergy and cannabis efficacy in neuropathic pain”.