The American College of Physicians (ACP) has issued new best practice advice for clinicians counseling patients about cannabis or cannabinoid use for chronic noncancer pain. The guidance, developed by ACP's Population Health and Medical Science Committee, addresses the growing prevalence of cannabis use among patients seeking pain relief and the limited clinical evidence supporting its effectiveness.

Key Recommendations

1. Counsel patients about benefits and harms when they consider starting or continuing cannabis or cannabinoids for chronic noncancer pain.
2. Specific patient subgroups should be advised that harms likely outweigh benefits, including young adults and adolescents, patients with current or past substance use disorder, those with serious mental illness, and frail patients at risk for falling.
3. Clinicians should advise against cannabis use in pregnant or breastfeeding patients or those trying to conceive.
4. Inhaled cannabis for pain management should not be recommended.

Evidence Base

The ACP recommendations are based on an Agency for Healthcare Research and Quality (AHRQ) living systematic review that identified 26 randomized controlled trials and 12 observational studies examining cannabis or cannabinoid effects on chronic noncancer pain compared with placebo or usual care.

"For many patients, the current evidence suggests that the harms of cannabis and cannabinoid use to manage chronic noncancer pain outweigh the small potential benefits," the ACP noted in the guidance, published in Annal of Internal Medicine.

Limited Benefits

The evidence revealed modest effectiveness at best. The most-studied cannabinoid formulations—nabiximols (not FDA-approved in the US) and synthetic THC preparations—demonstrated limited benefits. ACP noted the following:

• Nabiximols, with comparable amounts of THC and CBD, provided "small improvements in pain severity (approximately 0.5 to 1.0 points on a 0- to 10-point numerical rating scale) and function or disability (approximately 0.4-point improvement on a 0- to 10-point numerical rating scale)."
• High THC-CBD ratio synthetic products "may result in small improvements in pain severity (approximately 0.5- to 1.0-point improvement on 0- to 10-point numerical rating scale) but no change in overall function or disability."

The evidence was found to be "insufficient to show benefit for other types of chronic noncancer pain" beyond neuropathic pain, which was the focus of 19 of 26 randomized controlled trials, noted the ACP.

Documented Harms

The ACP guidance detailed multiple established and potential harms, including:

• Cannabis formulations with comparable THC and CBD "may result in a large increased risk for dizziness and sedation and a modest increased risk for nausea."
• Synthetic THC preparations "probably result in a large increase in the risk for dizziness" and "may result in a large increase in nausea and a modest increase in the risk for sedation."
• Long-term risks include cannabis use disorder, which affects 10% to 30% of people reporting past-year cannabis use, and cannabis withdrawal syndrome.
• Additional concerns include cognitive effects, mental health impacts, and physical health effects including cardiovascular, gastrointestinal, and pulmonary complications.

Special Population Considerations

The guidance emphasized particular caution for vulnerable groups. Adolescents and young adults face "adverse cognitive effects" and "a higher rate of psychotic symptoms and a higher incidence and earlier onset of psychotic spectrum disorders." Patients with mood disorders or serious mental illness may experience worsening of their condition.

Regarding pregnancy, the ACP noted: "After controlling for confounders, including tobacco use, cannabis use during pregnancy is associated with an increased risk for preterm birth (adjusted odds ratio across 12 studies, 1.42 [95% CI, 1.19 to 1.69]; low-certainty evidence)."

The ACP's best practice advice aims to equip clinicians with the information needed for meaningful patient discussions about cannabis use for chronic noncancer pain in an evolving medical and regulatory landscape.