CBD Showed Limited Effects on Opioid Withdrawal in Rats | Research

The takeaway

Oral CBD at two doses did not significantly reduce most physical or behavioral withdrawal symptoms in morphine-dependent rats, though some sex-specific effects emerged in the protracted phase.

Addiction researchers exploring CBD as a treatment tool, clinicians following CBD-for-opioids research, pharmacologists studying cannabinoid-opioid interactions.

What the researchers found

In a well-powered study (N=100, 50% female), researchers made rats dependent on morphine through 10 days of escalating doses (10–50 mg/kg, twice daily), then abruptly stopped and treated with oral CBD (10 or 30 mg/kg daily) or vehicle starting 14 hours after the last morphine injection.

The results were largely negative for CBD's ability to treat acute withdrawal. Morphine-dependent rats showed the expected withdrawal syndrome — weight loss, reduced food intake, somatic signs (body shakes, diarrhea), and pain sensitivity. CBD at either dose did not significantly reduce these acute withdrawal measures compared to vehicle.

In the protracted withdrawal phase (up to day 7), there were some signals: anxiety-like behavior measures showed potential CBD effects, but these appeared to differ between males and females. The overall pattern suggested that CBD's impact on opioid withdrawal — at least at these doses and in this model — was limited and potentially sex-dependent rather than broadly therapeutic.

Why it matters

CBD is being investigated as a potential treatment for opioid use disorder, with some observational studies suggesting benefit. This controlled animal study provides a reality check: in a well-powered experiment with both sexes, CBD did not meaningfully reduce acute opioid withdrawal symptoms. This is important context for the clinical enthusiasm surrounding CBD as an addiction treatment tool.

The numbers in context

100 rats (50 female). Morphine escalated from 10 to 50 mg/kg over 10 days. CBD doses: 10 and 30 mg/kg oral, daily. Neither CBD dose significantly reduced acute withdrawal measures. Some sex-specific effects in protracted phase anxiety measures.

How the study worked

100 Sprague-Dawley rats (50% female) received escalating morphine (10–50 mg/kg, twice daily) for 10 days. After abrupt discontinuation, rats received daily oral CBD (10 or 30 mg/kg) or vehicle. Withdrawal assessed through physical measures (body weight, food intake, somatic signs), pain sensitivity, and anxiety-like behaviors across acute (38-hour) and protracted (up to day 7) timepoints.

Who was studied

N=100 male and female Sprague-Dawley rats, administered morphine for opioid dependence study

What this study cannot tell us

Animal model — rat morphine withdrawal may not perfectly model human opioid withdrawal. Oral CBD dosing may not achieve optimal brain levels (bioavailability issues noted in RTHC-00246). Only two CBD doses tested; higher doses might show different effects. The 10-day morphine protocol produces moderate dependence; more severe dependence might respond differently.

How to read the evidence

Well-powered controlled animal experiment — rigorous within the preclinical framework but the negative results for acute withdrawal need human study confirmation before clinical conclusions.

When this study was published

Published in 2026, adding preclinical data to the active clinical investigation of CBD for opioid use disorder.

The bigger picture

This connects to RTHC-00228, which found CBD reduced opioid self-administration without reducing analgesia — suggesting CBD might help prevent relapse rather than treat active withdrawal. Together, these studies paint a nuanced picture: CBD may influence some aspects of the opioid addiction cycle (craving, self-administration) without being effective against the acute physical withdrawal that drives much of the clinical crisis. The sex-specific findings echo the broader pattern of sex differences in cannabinoid research (RTHC-00222, RTHC-00236, RTHC-00249).

Replication

Not stated in abstract.

Funding

Not reported in abstract.

Conflicts of interest

Not reported in abstract.

Questions still open

Would higher CBD doses or different formulations (with better bioavailability) show stronger effects? Is CBD's potential in opioid use disorder limited to the craving/relapse phase rather than acute withdrawal? Do the sex-specific effects in protracted withdrawal point to a meaningful biological difference or a statistical artifact?

Read the original research

Effects of oral cannabidiol (CBD) on spontaneous opioid withdrawal in male and female rats.

Experimental and clinical psychopharmacology

Experimental and Clinical Psychopharmacology is a peer-reviewed journal focusing on the effects of drugs on behavior and mental processes.

View on PubMed ↗Publisher’s paper ↗

Citation

Jenkins, Bryan W; Pang, Cerina; Kuang, Robbie Y; Weerts, Elise M; Moore, Catherine F. (2026). Effects of oral cannabidiol (CBD) on spontaneous opioid withdrawal in male and female rats.. Experimental and clinical psychopharmacology. https://doi.org/10.1037/pha0000826