Meeus, Mira, Ickmans, Kelly, Struyf, Filip et al. · Pain physician · 2013
This study tested whether acetaminophen (Tylenol) could help improve how the body's natural pain-blocking systems work in people with ME/CFS combined with fibromyalgia, compared to people with rheumatoid arthritis and healthy people. Researchers measured pain responses before and after taking acetaminophen or a placebo. The results were mixed: acetaminophen slightly helped pain thresholds in ME/CFS patients but actually made things slightly worse in arthritis patients and healthy controls, suggesting the drug affects different people very differently.
This is the first study directly comparing how acetaminophen affects central pain processing (temporal summation and pain inhibition) in ME/CFS patients versus other chronic pain populations. Understanding why ME/CFS patients respond differently to pain medications could lead to more targeted and effective treatment strategies, and the finding that CFS/FM shows greater central pain abnormalities highlights the distinct neurobiological features of ME/CFS.
This study does not prove that acetaminophen is an effective treatment for ME/CFS pain, as the positive effects were minimal and inconsistent. It does not establish whether improved pain thresholds in CFS/FM patients translate to clinically meaningful symptom relief. The single-dose, acute-response design does not address whether repeated acetaminophen use would produce different effects or whether these laboratory pain measures reflect real-world pain experiences.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Meeus, Mira, Ickmans, Kelly, Struyf, Filip, Hermans, Linda, Van Noesel, Kevin, Oderkerk, Jorinde, et al. (2013). Does acetaminophen activate endogenous pain inhibition in chronic fatigue syndrome/fibromyalgia and rheumatoid arthritis? A double-blind randomized controlled cross-over trial.. Pain physician. https://pubmed.ncbi.nlm.nih.gov/23511692/
BibTeX
@article{mecfsatlas-meeus-2013-does-acetaminophen,
author = {Meeus, Mira and Ickmans, Kelly and Struyf, Filip and Hermans, Linda and Van Noesel, Kevin and Oderkerk, Jorinde and Declerck, Luc S and Moorkens, Greta and Hans, Guy and Grosemans, Sofie and Nijs, Jo},
title = {Does acetaminophen activate endogenous pain inhibition in chronic fatigue syndrome/fibromyalgia and rheumatoid arthritis? A double-blind randomized controlled cross-over trial.},
journal = {Pain physician},
year = {2013},
note = {PubMed: 23511692},
url = {https://www.mecfsatlas.com/evidence/meeus-2013-does-acetaminophen},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/meeus-2013-does-acetaminophen
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