Cannabis is no longer viewed solely as a recreational substance; it is increasingly recognized for its therapeutic potential. In many parts of the world, laws have evolved to include the use of cannabis for medical purposes. The medical community hasn’t reached a clear consensus yet, and a recent study has only increased the uncertainty further.
A new meta-analysis covering 46 studies and 54,382 participants reveals a surprising pattern: regular cannabinoid use is associated with higher levels of both pro-inflammatory and anti-inflammatory biomarkers in the bloodstream. Rather than simply switching inflammatory responses on or off, cannabis appears to be modulating how the immune system functions.
Even without a diagnosed illness, changes in inflammation may signal subtle immune shifts that over time could lead to increased health risks. The findings are published in Brain Behavior and Immunity.
Studying the studies on effects of cannabis
Cannabinoids like THC and CBD are the main active compounds in cannabis that interact with the body’s endocannabinoid system. They are thought to affect the immune system through their interaction with CB1, CB2, and other receptors located on both innate (the body’s first line of defense) and adaptive (highly specific) immune cells. However, their impact on inflammation in healthy and psychiatric populations remains unclear. Previous research has been far from consistent. Some studies suggest cannabis may reduce inflammation, others indicate it could increase it, while some find no clear effect at all.
As more countries legalize cannabis and cannabinoid-based therapies gain popularity, many people, especially young users, are starting to see it as safe and beneficial. With use becoming so widespread, public health experts need clear, reliable evidence to understand how it could shape population health over the coming decades.
To better understand what the research to date has found, the researchers conducted a systematic review and meta-analysis. They started by searching five major scientific databases for all peer-reviewed research published up until late 2025 for studies comparing inflammation markers between adults who use cannabinoids and those who don’t.
The analysis included both healthy individuals and people with psychiatric disorders such as schizophrenia or substance use disorders, since these groups are more likely to use cannabis. They excluded individuals with physical illnesses, such as infections or chronic conditions, as well as pregnant women, to avoid other health factors influencing the results.
The collected data were then analyzed using a sophisticated tool called Bayesian multilevel meta-analysis. This allowed them to account for all 190 individual findings at once, including different biomarkers studied within each study and individual effect sizes. It also considered factors such as participant age and gender, the type of cannabinoid used (natural or synthetic), and how recently it was used, all of which could influence inflammation levels.
They found that regular use of cannabis products leads to a simultaneous rise in both pro-inflammatory and anti-inflammatory markers in the blood. Many people use CBD under the assumption that it is purely anti-inflammatory, yet the researchers found that in controlled clinical trials involving healthy individuals, it was associated with small increases in pro-inflammatory markers. The findings also highlight that product type plays a major role, as synthetic cannabinoids were linked to a much stronger increase in inflammatory signals compared to natural cannabis.
The researchers noted that the results uncover a more complex pattern of immune modulation rather than a simple increase or decrease in inflammation. This calls for further investigation, as even small changes in inflammation may indicate subtle immune disruption over time, which could eventually contribute to adverse physical and mental health outcomes.
Until future research offers new evidence that points in a different direction, this large overview of existing studies helps inform the future use of medical cannabis and make users aware of potential immune effects.