News & Announcements

Combining cannabis with an opioid did not improve acute pain for people with knee osteoarthritis (OA), according to results of a study published in the May issue of Anesthesiology.

Although animal studies have suggested that the 2 drugs might work better together to relieve pain, this randomized, double-blind, placebo-controlled study found no added benefit during laboratory pain testing. The findings showed that neither cannabis nor opioids alone provided significant pain relief and using them together did not improve results.

“Some patients believe combining cannabis with opioids can help with pain, and clinicians may recommend or prescribe it in states where cannabis is legal,” said Katrina R. Hamilton, PhD, lead author of the study. “Our study suggests that isn’t the case and patients may experience more side effects when the drugs are combined.”

Dr. Hamilton is from the Department of Psychology at Ohio University, Athens, Ohio, and the Department of Psychiatry and Behavioral Sciences at Johns Hopkins School of Medicine, Baltimore, Maryland.

Study Methods

The study included 21 patients with knee OA. Each took part in 4 sessions, receiving different combinations of pills each time:

• Two placebos
• Hydromorphone and a placebo
• Dronabinol and a placebo
• Hydromorphone and dronabinol

All patients received all 4 combinations in a random order.

The researchers used a range of tests to assess how the drugs affected pain, including:

• Sensitivity to pressure, heat, and cold
• How well participants’ bodies naturally reduced pain
• How much knee pain participants were experiencing

They also assessed thinking and memory, physical functioning, and how the drugs made participants feel overall (including side effects), to understand the full impact on both body and mind.

Study Findings

The researchers determined that taking opioids and cannabis, either alone or in combination, did not provide robust acute pain relief while undergoing laboratory pain testing.

The opioid alone reduced pain sensitivity, while the cannabis did not, but neither meaningfully reduced participants’ self-reported pain during the study visits.

When the 2 drugs were combined, side effects such as drowsiness, dizziness and impaired thinking were stronger and more noticeable, without added pain relief.

Real-World Usage

An accompanying editorial noted that the participants had never used cannabis before, that they received a single relatively high dose, and that the results may not fully represent how cannabis is used in the real world. Cannabis may still address symptoms related to pain, such as sleep, mood, and anxiety, even if its direct effect on pain is limited, the editorial said.

“In the real world, people often use cannabis differently, including lower starting doses, using gradually stronger doses, which may affect both benefits and side effects,” Dr. Hamilton said.

“More research is needed to better understand how cannabis affects pain when used in real-world settings.”

Sources

Boehnke KF. Opioids and cannabis: An uncertain combination? Anesthesiology. 2026 May 1;144(5):1048-1050. doi: 10.1097/ALN.0000000000005958. Epub 2026 Apr 14.

Hamilton, KR, Mun CJ, Sadik E, et al. Evaluating the acute effects of the cannabinoid dronabinol and the opioid hydromorphone alone and in combination: a double-blind, randomized, placebo-controlled trial in knee osteoarthritis. Anesthesiology. 2026 May 1;144(5):1187-1198. doi: 10.1097/ALN.0000000000005925. Epub 2025 Dec 31.