A large review of medical studies examined whether cannabis-based products can help people living with chronic pain, a condition defined as pain that lasts for months or even years. The analysis included data from more than 2,300 adults and focused on products containing different amounts of two well-known cannabis compounds: tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the compound responsible for the "high" associated with marijuana, while CBD does not cause intoxication and is often marketed for wellness and pain relief.

The review found that cannabis products with higher levels of THC compared to CBD may offer small, short-term improvements in pain levels and physical functioning. These modest benefits were most noticeable among people with nerve-related pain, also known as neuropathic pain, which can cause burning, tingling, or shooting sensations. However, the potential benefits came with drawbacks. Products higher in THC were also linked to a greater risk of common side effects. In contrast, products with low THC content, including CBD-only formulations, did not appear to meaningfully reduce pain. The findings were published in Annals of Internal Medicine.

How the Research Was Conducted

The review was led by researchers from Oregon Health & Science University working with other experts in the field. They analyzed 25 short-term, placebo-controlled randomized trials, which are considered one of the strongest types of clinical studies because they compare an active treatment to an inactive placebo. The goal was to update earlier evidence on how effective cannabis-based products are for chronic pain and how often they cause harm.

To better compare results across studies, the researchers grouped cannabis products in several ways. They classified cannabinoids based on the ratio of THC to CBD (high, comparable, low). They also noted whether the products were synthetic, meaning made in a laboratory, purified, or extracted directly from a cannabis plant. In addition, they examined how the products were taken, including oral forms such as pills, oromucosal sprays applied inside the mouth, and topical products applied to the skin. The team then measured changes in pain severity, physical function, and the occurrence of adverse events.

What the Results Showed

The data suggested that oral products containing only THC likely led to a slight reduction in pain severity. Among these, nabilone showed a moderate benefit, while dronabinol produced little or no meaningful improvement. Nabiximols, a product that contains both THC and CBD, slightly reduced pain but did not improve physical function, which includes activities such as walking, working, or completing daily tasks.

Across the studies, products with high or comparable THC levels were consistently associated with higher rates of side effects. These adverse events included dizziness, sedation, and nausea, with increases described as moderate to large. Because most of the trials were short in duration, the authors emphasized that there is still limited information about long-term safety and effectiveness. They also noted that many types of cannabis products commonly used by the public have not yet been well studied.