![[Adobe Stock]](https://sp-ao.shortpixel.ai/client/to_webp,q_glossy,ret_img,w_750,h_375/https://www.psypost.org/wp-content/uploads/2026/11/psychedelic-pattern-750x375.jpg)
A systematic review and meta-analysis found that most laboratory and animal studies report anti-inflammatory effects of psychedelics, but mainly when inflammation is already present. In mice and rats, psychedelics reduced inflammatory markers in animals with induced inflammation but not in healthy animals, while the small number of human studies produced mixed results. The paper was published in Brain, Behavior, and Immunity.
Psychedelics are psychoactive substances that alter perception, mood, and thought processes. Some of the most widely used psychedelics include psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine (DMT). Although they are illicit in most jurisdictions, they are being studied for their potential to treat conditions that do not respond to existing treatments.
Using psychedelics in controlled therapeutic settings is called psychedelic therapy. Research suggests that it may provide lasting benefits for people with psychiatric and neurological conditions such as depression, anorexia, Parkinson’s disease, and migraine. Although most research has focused on how psychedelics affect the brain, scientists are increasingly interested in their effects on other bodily systems, particularly the immune system. This is important because inflammation can influence brain function and behavior, while prolonged inflammation is associated with an increased risk of psychiatric and neurological disorders.
Some researchers therefore suspect that the therapeutic benefits of psychedelics may partly result from their ability to regulate immune responses and reduce inflammation. However, different psychedelics interact with the biological systems of the body in different ways, so further research is needed to determine how their effects on the immune system contribute to potential therapeutic benefits.
Don’t miss the next big psychology finding
Every morning, PsyPost sends a short briefing on the most interesting new peer-reviewed research in psychology and neuroscience.
Study author Anna Skovgaard Lerche and colleagues, including researchers at the University of California, San Francisco, and the University of Copenhagen, wanted to investigate the effects of psychedelics on the immune system. They hypothesized that psychedelics would have anti-inflammatory effects that depend on context, such as whether inflammation is already present. To test this, they conducted a systematic review and meta-analysis of published studies.
The review included studies of cells grown in the laboratory (in vitro studies), studies of live animals (in vivo studies), and studies of humans. To be included, a study needed to examine the effects of psychedelics on the immune system and to have been published in English in a peer-reviewed journal. The researchers defined psychedelics as “drugs with primary effect on the 5-HT2AR that induce a psychedelic subjective experience in humans or head-twitch in mice.” The 5-HT2A receptor is a receptor for the neurotransmitter serotonin and the primary target through which classic psychedelics produce their psychedelic effects.
Drugs such as MDMA and ketamine, which do not act primarily through this receptor, were excluded. The researchers searched several databases of scientific literature, including PubMed and EMBASE, for studies published through February 2026. Of 9,195 records screened, 61 studies met the criteria: 24 in vitro studies, 30 studies of non-human animals, and seven human studies that included data from 10 separate trials.
For the meta-analysis, the researchers excluded some animal studies, including one conducted on zebrafish, studies that measured immune markers not examined in enough other studies, studies that used very high doses, and one study that used chronic dosing to induce a disease model. The final meta-analysis included 18 studies of mice and rats and four human studies with data from six trials.
Results of the systematic review showed that 19 of the 24 in vitro studies and 25 of the 30 animal studies reported anti-inflammatory effects of psychedelics. These effects depended on context. Among studies in which inflammation had been induced, 19 of 21 in vitro studies and all 24 animal studies reported anti-inflammatory effects. In contrast, five of the six animal studies without an inflammatory challenge reported proinflammatory effects, mostly in studies using very high doses or repeated dosing over weeks.
Human studies produced mixed results. Of the 10 human trials, three found anti-inflammatory effects, three found proinflammatory effects, and four found no effects. Only one trial included a group of participants with confirmed elevated inflammation: a study of ayahuasca in people with treatment-resistant depression, which found that ayahuasca reduced the inflammatory marker C-reactive protein compared with placebo. Some of the proinflammatory findings in humans involved short-term shifts in immune cells within hours of dosing, similar to those produced by the stimulant dextroamphetamine.
The meta-analysis of animal studies showed that psychedelics were associated with a large decrease in proinflammatory cytokines, signaling molecules that promote inflammation, in rodents with induced inflammation. In healthy rodents, psychedelics had no effect on these markers. Most of the interpretable data came from studies of DOI, a synthetic psychedelic used mainly in research, and the clearest reductions involved the cytokines IL-1β, IL-6, and TNF-α in the brain and blood.
There were too few human studies for a reliable meta-analysis. The researchers note that serotonin 2A receptors appear to drive the anti-inflammatory effects of DOI, while DMT appears to act mainly through a different receptor called sigma-1, suggesting that different psychedelics may influence inflammation in different ways.
“Thus, while serotonergic psychedelics reduce proinflammatory cytokines in preclinical models of increased baseline inflammation, limited human evidence precludes conclusions about their translational potential,” the study authors concluded.
The study contributes to the scientific understanding of the immunomodulatory effects of psychedelics. However, most of the evidence for anti-inflammatory effects came from animal and laboratory studies, while human studies painted a mixed picture. Most human studies did not include people with elevated inflammation, which may have limited the opportunity to detect anti-inflammatory effects.
The animal studies also showed signs of small-study effects, meaning smaller studies tended to report larger effects, which can indicate publication bias. An adjusted estimate that accounted for this pattern was much smaller and not statistically distinguishable from zero, although that analysis combined studies of inflamed and healthy animals. The studies also varied widely in drugs, doses, timing, and immune markers, and many were rated as having a medium or high risk of bias.
Senior author Aoife O’Donovan has received funding from Silo Pharma for studies in this area, and co-author Boris Heifets serves on the scientific advisory boards of Journey Clinical and Osmind and consults for Arcadia Medicine. The authors state that the funders had no role in the review.
The paper, “Are psychedelics anti-inflammatory? A systematic review and meta-analysis of studies examining the immunomodulatory effects of serotonergic psychedelics,” was authored by Anna Skovgaard Lerche, D. Parker Kelley, Michael E. Benros, Gerald Billac, Ellen R. Bradley, Boris Heifets, Joshua Woolley, Kristen Nishimi, and Aoife O’Donovan.
