Study shows legal marijuana products too strong for pain relief

A new study has revealed that most legal marijuana products supplied to medical dispensaries are significantly higher in strength than recommended levels for the treatment of chronic pain.

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THC levels in medical marijuana should be no more than 5%

In a study published this week in the journal PLOS ONE, scientists at the Wake Forest School of Medicine announced that over 90% of legal marijuana products are far more potent than clinical tests recommended they should be.

An estimated three and a half million people in the US take medical marijuana for various reasons. Chronic pain relief is a major reason for being prescribed this kind of product, however, it is also used to treat nausea caused by chemotherapy, muscle stiffness and spasms that are characteristic of multiple sclerosis (MS), and severe forms of epilepsy.

With such a vast number of people taking the substance for a wide range of conditions, it is essential that medical marijuana meets guidelines that have been laid out by scientific research in order to protect users from negative side effects.

Higher potency products carry greater risks of inducing substance-use disorders, therefore, it is important that strengths of medically available marijuana products lie within the levels deemed both effective and safe by clinical studies. High-exposure to tetrahydrocannabinol (THC), the psychoactive substance in cannabis, can have negative impacts on a person’s health, which is then counterintuitive to using these products therapeutically.

Previously, multiple studies have revealed that for a marijuana product to be effective at alleviating chronic pain with minimal adverse effects it should contain no more than 5% THC. Researchers at the Wake Forest School of Medicine set out to determine whether these levels are being maintained in marijuana products that are being supplied to medical dispensaries.

Most medical marijuana products contain more than 10% THC

The team of researchers in Wisconsin took samples from 653 dispensaries across the states of California, Colorado, Maine, Massachusetts, New Hampshire, New Mexico, Rhode Island, Vermont, and Washington. In total, 8,505 cannabis products were analyzed.

Researchers measured and recorded the levels of THC in the products, as well as concentrations of cannabidiol (CBD), the other major substance in cannabis, however, unlike THC it is non-psychoactive. All the samples taken were from products supplied by legal dispensary websites.

The results showed that most products sampled that were available in medical dispensaries had greater than 10% concentrations of THC, with a significant amount containing 15% of the substance, much higher than the recommended 5%, reaching the same levels as products available at dispensaries supplying recreational marijuana.

Most people using medical marijuana are using it to treat chronic pain (roughly 60-80% of users). Given that concentrations of THC are higher than they are expected to be in products supplied by medical dispensaries, these people are being put at risk of developing dependency issues, as well as tolerance, leading to them requiring higher and higher concentrations to feel the same level of pain relief as time goes on.

Better regulation of medical marijuana products needed

The results highlight the urgent need for better regulation of medical marijuana products. Concentrations of THC in these products must be monitored and kept to the recommended levels to protect those using them. In a similar way to how over-the-counter pain medications are regulated by the FDA, medical marijuana products should also be strictly monitored.

The study acts as a warning to policymakers that patients using medical marijuana are at risk of severe side effects if the products continue to not be regulated. Hopefully, this research will encourage systems to be put in place to ensure levels of THC are kept to no more than 5%.


Study shows legal marijuana products too strong for pain relief. Eurekalert. Available at:

Sarah Moore

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Sarah Moore

After studying Psychology and then Neuroscience, Sarah quickly found her enjoyment for researching and writing research papers; turning to a passion to connect ideas with people through writing.


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