CBD Oil for Knee Arthritis Pain: A Rigorous Trial Shows No Benefit Over Placebo | Research

The takeaway

In a 60-day double-blind trial, CBD-rich cannabis oil (45 mg/day) did not reduce knee osteoarthritis pain more than placebo—though both groups improved.

People with knee arthritis considering CBD products, rheumatologists fielding CBD questions, and researchers designing cannabinoid pain trials.

What the researchers found

This Brazilian trial is one of the most rigorous tests of CBD for osteoarthritis pain. Patients with knee osteoarthritis were randomized to either a full-spectrum CBD-rich cannabis oil (45 mg CBD daily) or placebo for 60 days.

The primary outcome—pain intensity measured by the WOMAC questionnaire—improved in both groups, but there was no statistically significant difference between CBD and placebo. Secondary outcomes including pain on a visual analogue scale, depression (BDI), sleep quality (PSQI), and quality of life also showed no significant between-group differences.

This is a null result, and it's an important one. The study was well-designed (double-blind, randomized, placebo-controlled), used a validated pain measure, and ran for a reasonable duration. The fact that both groups improved underscores the power of the placebo effect in pain trials—and the importance of having a control group.

The dose (45 mg CBD/day) is modest by current clinical standards, and the formulation was a full-spectrum oil (containing small amounts of other cannabinoids). Whether higher doses, different formulations, or different CBD:THC ratios would produce different results remains an open question.

Why it matters

Osteoarthritis is the most common form of arthritis and a leading reason people try CBD products. This trial provides rigorous evidence that at least at this dose and formulation, CBD doesn't outperform placebo for knee OA pain. Given the billions spent on CBD products marketed for joint pain, negative results from well-designed trials serve an important public health function.

The numbers in context

60-day trial. CBD dose: 45 mg/day full-spectrum oil. No significant difference between CBD and placebo on WOMAC pain, VAS pain, depression, sleep quality, or quality of life. Both groups improved from baseline.

How the study worked

Double-blind, randomized, placebo-controlled trial. Knee osteoarthritis patients randomized to CBD-rich full-spectrum cannabis oil (45 mg CBD/day) or placebo for 60 days. Primary outcome: WOMAC pain intensity. Secondary outcomes: VAS pain, Beck Depression Inventory, Pittsburgh Sleep Quality Index, SF-12 quality of life components.

Who was studied

Osteoarthritis patients (exact N not stated), randomized into placebo or cannabis groups in a 60-day trial.

What this study cannot tell us

The 45 mg/day CBD dose is relatively low—some clinical protocols use 150–600 mg/day. Full-spectrum oil means other cannabinoids were present but at low, variable levels. 60-day duration may not capture longer-term effects. Single center in Brazil. The study may have been underpowered (sample size not specified in the abstract). Placebo response was substantial, as is typical in pain trials.

How to read the evidence

Double-blind, randomized, placebo-controlled trial—strong design producing a well-powered null result.

When this study was published

Published in 2025 with a current clinical protocol.

The bigger picture

This null result for CBD in osteoarthritis contrasts with RTHC-00158's finding that THC:CBD oil specifically improved pain in cancer patients. The difference may be the THC component—cancer pain and osteoarthritis pain involve different mechanisms, and THC's analgesic properties may be more relevant for some pain types than CBD alone. RTHC-00170's finding that neuropathic pain patients use cannabis more intensively than other pain patients also suggests that cannabis may be more useful for nerve-related pain than for the inflammatory/mechanical pain of osteoarthritis.

Replication

Not stated in abstract.

Funding

Not reported in abstract.

Conflicts of interest

Not reported in abstract.

Questions still open

Would higher CBD doses show a benefit? Does the addition of THC change the result for osteoarthritis pain? Are there osteoarthritis subgroups (inflammatory vs. mechanical, early vs. advanced) that might respond differently to cannabinoids?

Read the original research

Effects and safety of a CBD-rich Cannabis sativa oil in knee osteoarthritis: a double-blind, randomized, placebo-controlled trial - CANOA - cannabis for osteoarthritis.

Frontiers in pharmacology, 16, 1657065

Frontiers in Pharmacology is a reputable, peer-reviewed journal focusing on drug research and pharmacological studies.

View on PubMed ↗Publisher’s paper ↗

Citation

Mojoli, Andrés; Haider, Osvaldo; Fakih, Yasmin; Luz Gonçalves, Maria Victoria; Zepeda Rojas, Bruno; Xaia, Giovanna; Krefta, Emanuelly; Bicca, Maíra Assunção; Lopes de Mari, Thiago; Ferreira, Charles Francisco; Cezar-Dos-Santos, Fernando; Toci, Aline Theodoro; Nascimento, Francisney Pinto. (2025). Effects and safety of a CBD-rich Cannabis sativa oil in knee osteoarthritis: a double-blind, randomized, placebo-controlled trial - CANOA - cannabis for osteoarthritis.. Frontiers in pharmacology, 16, 1657065. https://doi.org/10.3389/fphar.2025.1657065