. 2024 May 8;17(5):e13812. doi: 10.1111/cts.13812

TABLE 2.

Interaction between opioids and cannabis, based on case reports.

Drugs	Probability	Severity	Observed effects	Patient outcomes	Recommendation	References
Opioids
Methadone (Victim—CYP3A4 and CYP2C19 inhibition)	Defined	Moderate (116.8%)	Discontinuing CBD oil led to an overall decline in the methadone serum levels. Specifically, the serum methadone level was noted to be 271 ng/mL (2 days after stopping CBD), followed by 149 ng/mL (7 days after stopping CBD) and 125 ng/mL (14 days after stopping CBD)	A case report of a 13‐year‐old patient recorded symptoms of increased fatigue and somnolence, which worsened upon admission as the pupils were minimally reactive (~2 mm). Co‐administering methadone and CBD was believed to contribute to the adverse effects reported because an improvement in the symptoms occurred with CBD withdrawal	Implement carer education for potential cannabis–drug interactions. Provide suggestions on other supportive therapies to manage the specific symptoms that arise during methadone treatment to avoid the use of CBD	⁸

Drugs

Probability

Severity

Observed effects

Patient outcomes

Recommendation

References

Opioids

Methadone (Victim—CYP3A4 and CYP2C19 inhibition)

Defined

Moderate (116.8%)

Discontinuing CBD oil led to an overall decline in the methadone serum levels. Specifically, the serum methadone level was noted to be 271 ng/mL (2 days after stopping CBD), followed by 149 ng/mL (7 days after stopping CBD) and 125 ng/mL (14 days after stopping CBD)

A case report of a 13‐year‐old patient recorded symptoms of increased fatigue and somnolence, which worsened upon admission as the pupils were minimally reactive (~2 mm).

Co‐administering methadone and CBD was believed to contribute to the adverse effects reported because an improvement in the symptoms occurred with CBD withdrawal

Implement carer education for potential cannabis–drug interactions. Provide suggestions on other supportive therapies to manage the specific symptoms that arise during methadone treatment to avoid the use of CBD

⁸