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July 2020

Be Aware of New Potential CBD Drug Interaction

A new report suggests that taking cannabidiol (CBD) might increase methadone levels and increase its side effects. This is especially concerning in chronic pain settings such as cancer.

A 13-year-old patient with chronic cancer pain who was previously stabilized on methadone 7.5 mg twice daily was admitted to the ER with opioid-related side effects. These side effects started 5 days prior to the ER visit, which occurred about 2 weeks after her parents increased her dose of CBD oil 4-fold. After stopping CBD, the side effects resolved. CBD may increase methadone levels by inhibiting the cytochrome P450 3A4 (CYP3A4) and CYP2C19 enzymes, which metabolize methadone. This is the first case report suggesting there is an interaction between CBD and methadone. The interaction appears to be dose-dependent – in this case, it occurred with a very high dose of CBD but not with a much lower dose. More evidence is needed to verify this interaction and to determine the CBD dose threshold at which it might occur. 

Many patients and their families don’t disclose the use of natural medicines such as CBD and other cannabis products to their healthcare providers. It’s important to discuss the use of all cannabis-derived products with patients and their families. Healthcare providers should ask directly about CBD use and be aware of its potential drug interactions.

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