Psychedelics and the immune system: exciting results are arriving! In a placebo-controlled study of 60 healthy volunteers, IL-6 and CRP, two key markers of inflammation, were still lower a full week after a single dose of psilocybin. After ayahuasca, C-reactive protein fell in people with treatment-resistant depression, and bigger drops went with lower depression scores. And a systematic review of preclinical studies found a decrease in at least one inflammatory cytokine in 29 of 36 studies. Encouraging to see this science growing, with more studies arriving all the time!

Key studies

Study 1. Psilocybin in 60 healthy volunteers (Mason, 2023)

Bigger drops in IL-6 and CRP a week after psilocybin went with more persisting positive mood and social effects in a placebo-controlled study of 60 healthy volunteers!

In a placebo-controlled study, researchers gave 60 healthy volunteers a single dose of psilocybin or placebo and measured inflammatory markers in the blood on the day and seven days later. Researchers reported that psilocybin immediately lowered tumor necrosis factor-alpha (TNF-α), and that interleukin 6 (IL-6) and C-reactive protein (CRP) stayed lower a full week later! The bigger the drop in IL-6 and CRP, the more persisting positive mood and social effects participants reported.

“Additionally, the more of a reduction in IL-6 and CRP seven days after psilocybin, the more persisting positive mood and social effects participants reported.”

Abstract of the published study (text from Europe PMC), key sentence highlighted in yellow. Source: Mason NL, Szabo A, Kuypers KPC, et al. Psilocybin induces acute and persisting alterations in immune status in healthy volunteers: An experimental, placebo-controlled study. Brain Behav Immun. 2023;114:299-310. https://doi.org/10.1016/j.bbi.2023.09.004

Study 2. Ayahuasca in 28 people with treatment-resistant depression and 45 healthy controls (Galvão-Coelho, 2020)

Ayahuasca lowered C-reactive protein in people with treatment-resistant depression and in healthy controls, but placebo did not, and bigger drops went with lower depression scores (correlation +0.57)!

In a double-blind, placebo-controlled trial, researchers measured C-reactive protein (CRP) in the blood of 28 people with treatment-resistant depression and 45 healthy controls, before and 48 hours after ayahuasca or placebo. Researchers reported a significant reduction in CRP across time in both patients and controls given ayahuasca, but not placebo! In patients, larger CRP drops went with lower depressive symptoms (a correlation of +0.57), and the authors said the findings enhance understanding of the biological mechanisms behind the observed antidepressant effects of ayahuasca.

“We observed a significant reduction of C-reactive protein levels across time in both patients and controls treated with ayahuasca, but not with placebo.”

Abstract of the published study (text from Europe PMC), key sentence highlighted in yellow. Source: Galvão-Coelho NL, de Menezes Galvão AC, de Almeida RN, et al. Changes in inflammatory biomarkers are related to the antidepressant effects of Ayahuasca. J Psychopharmacol. 2020;34(10):1125-1133. https://doi.org/10.1177/0269881120936486

Study 3. Classic psychedelics and inflammation in 40 preclinical studies (Low, 2025)

29 of 36 preclinical studies measuring cytokines found a decrease in at least one inflammatory cytokine after classic psychedelics!

In a systematic review of 40 preclinical (cell and animal) studies of classic psychedelics such as psilocybin, LSD and DMT, drawn from 2,822 eligible articles, researchers looked at inflammatory markers after psychedelic administration. Researchers reported that in the 36 studies that measured inflammatory cytokines, 29 observed a decrease in at least one inflammatory cytokine! They also reported that classic psychedelics were found to alleviate pre-existing inflammation, and anticipated that the findings will inform future clinical trials.

“In 36 studies where inflammatory cytokine levels were measured following psychedelic administration, a decrease in at least one inflammatory cytokine was observed in 29 studies.”

Abstract of the published study (text from Europe PMC), key sentence highlighted in yellow. Source: Low ZXB, Ng WS, Lim ESY, et al. The immunomodulatory effects of classical psychedelics: A systematic review of preclinical studies. Prog Neuropsychopharmacol Biol Psychiatry. 2025;136:111139. https://doi.org/10.1016/j.pnpbp.2024.111139

Study 4. Psychedelics and the immune system, a review in the British Journal of Pharmacology (Qureshi, 2026)

A British Journal of Pharmacology review: psychedelics reduced inflammation in animal models of asthma and other inflammatory diseases, and early clinical studies showed an impact on circulating cytokine levels!

In a review of the research on psychedelics and inflammation, researchers described growing evidence that psychedelics modulate immune responses, including inhibiting pro-inflammatory cytokine release! Researchers reported that psychedelics such as (R)-DOI reduced inflammation in animal models of acute and chronic inflammatory disease such as asthma, and that some clinical studies with psilocybin showed an impact on circulating cytokine levels. The authors said these data emphasize the promise of approaches that target inflammation.

“Furthermore, in vivo studies demonstrate that psychedelics, like (R)-DOI, reduce inflammation in animal models of acute and chronic inflammatory disease such as asthma.”

Abstract of the published study (text from Europe PMC), key sentence highlighted in yellow. Source: Qureshi O, Cowley J, Pegg A, et al. Are we hallucinating or can psychedelic drugs modulate the immune system to control inflammation? Br J Pharmacol. 2026;183(14):4006-4021. https://doi.org/10.1111/bph.70138

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