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With each passing day, cannabis is gaining further mainstream acceptance as a safe and effective form of medication. 

Dozens of states have legalized medical cannabis to treat various medical conditions, from nausea to PTSD to inflammatory diseases. In addition, 18 states have legalized adult-use (“recreational”) cannabis. And across the country, an unknown number of people use cannabis to self-medicate, including those without a medical marijuana prescription. 

For many health conditions, cannabis can be highly effective and safer than other prescription medications, such as opioids. 

But while legal cannabis is considered a generally safe medication, it is not entirely without risk.

What are the potential risks of medical cannabis?

The Mayo Clinic listed the possible side effects of medical marijuana as follows:

  • Increased heart rate 
  • Dizziness 
  • Impaired concentration and memory 
  • Slower reaction times 
  • Negative drug-to-drug interactions 
  • Increased risk of heart attack and stroke 
  • Increased appetite 
  • Potential for addiction 
  • Hallucinations or mental illness 
  • Withdrawal symptoms

Penn State College of Medicine research has found 57 potential drug interactions for cannabinoids. Some potentially severe complications include Warfarin, a popular blood thinner, the thyroid medication levothyroxine, and seizure medications like clobazam, lamotrigine, and valproate.

A June 2021 comprehensive review in the European Journal of Internal Medicine advised on the safe application of cannabinoid medication. 

These include screening for potential precautions, contraindications, and drug interactions before starting medical cannabis treatment. The paper also calls for weighing the risk vs. benefits of medical cannabis use and the intake method (oral administration, inhalation, etc.). In addition, the paper stated that new patients should start with a low dose and slow titration method and have regular follow-ups to assess effectiveness, adverse events, and drug interactions. 

What is the role of a pharmacist in medical cannabis?

Several states have laws requiring the involvement of pharmacists or healthcare professionals in dispensing medical cannabis. 

Connecticut was the first state to enact such a law. The state requires a board-certified pharmacist to be onsite to dispense medical cannabis. Other states have similar laws. In Pennsylvania, for instance, a pharmacist or physician must be on staff, while medical dispensaries are licensed as pharmacies in Louisiana. 

In a 2020 interview, Secretary of the Board of Directors of the International Society of Cannabis Pharmacists (ISCPh) Jeffrey Lombardo stated that the pharmacist’s primary role “is to perform a drug-drug interaction check and look for potential clinical contraindications to the product, followed by a discussion with the patient around the evidence-based literature and the therapeutic benefits of cannabis, as it relates to the patient’s specific qualifying condition.” 

Lombardo also mentioned Epidiolex, the first FDA-approved cannabis medication. He said its potential to cause elevated enzyme levels requires careful monitoring by a pharmacist.

Lombardo added, “like other medications, medical cannabis needs to be titrated to the desired effect while keeping a close eye on potential side effects. When cannabis is combined with a patient’s established medication regimen, there can be a positive and negative synergistic effect.”

In a 2019 article in the Journal of the American Pharmacists Association (“Pharmacists and the future of cannabis medicine”), the authors state that “pharmacists are uniquely qualified to ensure the safe and effective use of cannabinoids.” 

The authors wrote that pharmacists “should leverage their skills by guiding product selection, dosing, identifying drug interactions, adverse effects, and educating patients on safe and effective cannabis use, whether it be THC, CBD, or a combination thereof.”

The paper also called for greater instruction on the endocannabinoid system and cannabinoid pharmacotherapy in the pharmacy school curriculum.

The need for further education and strict labeling requirements 

The need for additional cannabis and cannabinoid education is expressed in a 2018 position paper by the International Society of Cannabis Pharmacists (ICSPH). The paper states that “the endocannabinoid system and its manipulation by phytocannabinoids requires proper education in pharmacy, nursing, and medical schools.”

The paper states that increased access to regulated cannabis “may also lead to potential medication interactions and subsequent preventable harm.” 

It calls for “unbiased education” that covers the basic functions of the endocannabinoid system and potential health risks of phytocannabinoids.

Their recommendations include a detailed listing of the cannabinoids, terpenes, chemovar, active ingredients, and potential allergens and drug interactions. In addition, they call for detailed dosage descriptions for inhalation, oral, topical, transdermal, and suppository formulations of cannabinoid medicines. The CSPH also has a 2019 position paper that calls for better drug labeling for cannabis products. 

The lack of standardization in cannabis products 

One of the critical patient care issues in medical cannabis is the lack of standardization. 

Joseph Friedman, the chief operations officer at an Illinois dispensary, told Pharmacy Today, ​​“the problem is standardization—every dispensary’s product is different. Manufacturers may have similar dosages of THC [tetrahydrocannabinol] and CBD [cannabidiol], but the varying excipients may potentially alter the absorption, distribution, and metabolism.”

According to Melani Bersten, a dispensary pharmacist in Minnesota, the lack of standardization means that “our only solution under the current legal restrictions is to start low and go slow and prepare our patients for the experimental nature of the medicine.”

The importance of safety and "starting low and going slow"

Cannabis has been used as a natural medicine since ancient times. But legal medical cannabis is still relatively new, and medical cannabis products don’t have the standardization of more conventional forms of prescription drugs. 

Until standardization becomes the norm, dispensaries must ensure they meet cannabis compliance requirements for on-site healthcare professionals. In states without this requirement, dispensary personnel who are not licensed healthcare professionals should avoid making potentially risky treatment recommendations.

The advice is pretty straightforward for new medical cannabis patients: start low, go slow, and keep your doctor informed on how medical marijuana treatment is working for you. 

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Ben Hartman, Content Manager

Ben Hartman is a cannabis writing and marketing professional with over 15 years of experience in journalism and digital content creation. Ben was formerly the senior writer and research and analysis lead for The Cannigma.

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