E1 ReplicatedModerate confidencePEM unclearRCTPeer-reviewedMachine draft
A randomized, placebo-controlled, double-blinded trial of duloxetine in the treatment of general fatigue in patients with chronic fatigue syndrome.
Arnold, Lesley M, Blom, Thomas J, Welge, Jeffrey A et al. · Psychosomatics · 2015 · DOI
Quick Summary
This study tested whether duloxetine, a medication that affects mood and pain, could help reduce fatigue in people with ME/CFS. Over 12 weeks, 60 patients either took duloxetine or a placebo (dummy pill). While the medication did not significantly improve general fatigue compared to placebo, it did help some people with mental fatigue, pain, and overall symptom severity.
Why It Matters
This study addresses an important clinical question about whether serotonin-norepinephrine reuptake inhibitors can ameliorate ME/CFS fatigue and comorbid symptoms. The mixed results—negative for primary outcome but positive for pain and secondary fatigue measures—help clarify which symptom domains may respond to duloxetine and inform treatment discussions between patients and clinicians.
Observed Findings
- General fatigue (primary outcome) did not significantly improve with duloxetine versus placebo (P=0.23)
- Mental fatigue scores showed significant improvement with duloxetine compared to placebo
- Brief Pain Inventory average pain severity and interference scores improved significantly in the duloxetine group
- Short Form-36 bodily pain domain scores were significantly better in the duloxetine group
- Clinical Global Impression of Severity scores improved significantly with duloxetine versus placebo
Inferred Conclusions
- Duloxetine did not significantly reduce core general fatigue in ME/CFS patients over 12 weeks
- Duloxetine may be efficacious for specific symptom domains including mental fatigue, pain, and overall severity in ME/CFS
- Larger controlled trials are needed to confirm efficacy in secondary symptom domains and establish clinical significance
- Duloxetine was well tolerated in this ME/CFS population
Remaining Questions
- Would longer treatment duration (>12 weeks) show improvement in general fatigue with duloxetine?
- Are there ME/CFS patient subgroups (e.g., based on pain predominance or psychiatric comorbidity) more likely to benefit from duloxetine?
What This Study Does Not Prove
This study does not prove that duloxetine is ineffective for ME/CFS, only that it did not significantly improve general fatigue in this 12-week trial. The improvement in secondary measures does not establish that these benefits meaningfully improve daily function or quality of life. The sample size (n=60) and single dosing range limit generalizability to different patient populations or dosing strategies.
Tags
Symptom:Cognitive DysfunctionPainFatigue
Method Flag:Weak Case DefinitionSmall Sample
Metadata
- DOI
- 10.1016/j.psym.2014.12.003
- PMID
- 25660434
- Review status
- Machine draft
- Evidence level
- Replicated human evidence from multiple independent studies
- Last updated
- 8 April 2026
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 →
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