Summary
N-Acetylcysteine (NAC) is tracked by OSMF as an investigational option for ME/CFS; no regulator has approved it for this indication, and most post-viral conditions have no approved disease-modifying therapy at all. ClinicalTrials.gov lists 3 registered trials linking N-Acetylcysteine (NAC) to ME/CFS: 1 is active or not yet recruiting; 2 are terminated, withdrawn, suspended or of unknown status. The most advanced is Phase 2 (NCT04542161, sponsored by Weill Medical College of Cornell University). The largest enrolment is 200 participants (NCT03502044). Registration activity spans 2010 to 2020. The literature layer holds 8 publications for this pair: 8 curated references. Publication years run from 2025 to 2026. Items here are search-derived or curated references rather than classified trial reports; treat them as leads to read, not as graded evidence.
Myalgic Encephalomyelitis / Chronic Fatigue Syndrome is tracked on the OSMF post-viral programme alongside ME/CFS, Long COVID, POTS and MCAS. Across the programme, 191 candidate agents are logged for ME/CFS, most of them preliminary; this page isolates the record for one of them.
Evidence table
| Evidence tier | B · Moderate |
|---|---|
| Evidence score | 28.0 (trials 6.0, literature 12.0, tier 10, approved bonus 0.0) |
| Registered trials | 3 total: 0 recruiting, 1 active / not yet recruiting, 0 completed, 2 other |
| Linked publications | 8 (8 curated references) |
| Agent type | Behavioural (Behavioral / Protocol / Exercise, Supplement / Nutraceutical) |
| Development stage (any indication) | Investigational |
| Mechanism / class | Anti-inflammatory; Immunomodulatory; Neurological / Autonomic |
| Data sources | OSMF therapeutic agent database, ClinicalTrials.gov, PubMed |
| Also known as | N-Acetylcysteine (NAC) |
How the evidence score is calculated
- Each registered trial scores by status (recruiting / active / enrolling 3, completed 2.5, not yet recruiting 2, unknown 1, terminated / withdrawn / suspended 0.5) plus a phase bonus (phase 3-4 +2, phase 2 +1, phase 1 +0.5). The trial component is capped at 30.
- Each literature item scores by design (Cochrane review 5, meta-analysis 4, systematic review 3, RCT 3, clinical trial publication 2, curated reference 1.5, other PubMed record 1). The literature component is capped at 30.
- The existing evidence tier adds 15 (A / Strong), 10 (B / Moderate), 5 (C / Preliminary) or 0 (D / Anecdotal).
- Agents approved for any indication (max clinical phase 4) add 5, because an approved agent has an established safety profile that lowers the barrier to repurposing trials.
- The score ranks what has been studied, not what works. It does not read effect sizes or directions of effect.
Registered clinical trials
| NCT ID | Title | Status | Phase | Enrolment |
|---|---|---|---|---|
| NCT04542161 | Assessment of N-Acetylcysteine as Therapy for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Weill Medical College of Cornell University · 2020 | active, not recruiting | Phase 2 | 95 |
| NCT03502044 | New MRT Imaging Biomarkers and Treatment With Kinetic Oscillatory Stimulation (KOS) in Nasal Cavity for Myalgic Encephalomyelitis/Chronic Fa Karolinska University Hospital · 2018 | status unknown | Not applicable | 200 |
| NCT01154647 | Pain Inhibition in Patients With Rheumatoid Arthritis and Central Sensitivity Syndromes Vrije Universiteit Brussel · 2010 | status unknown | Not applicable | 70 |
Published literature
- Curated reference (OSMF) Mechanistic Insights and Emerging Therapeutic Strategies in Recurrent Pericarditis.2026
- Curated reference (OSMF) What is the Role of "the Psyche"? Long COVID and ME/CFS as Test Cases for Evidence-Based and Patient-Centered Psychiatry and Psychotherapy.2026
- Curated reference (OSMF) [Post-COVID: An inventory focusing on the key complaints PEM and POTS].2026
- Curated reference (OSMF) Assessment of the accuracy of initial diagnoses and the frequency of clinical forms of Lyme disease among hospitalized patients: a single-ce2025
- Curated reference PubMed record PMID 41042957
- Curated reference PubMed record PMID 41835354
- Curated reference PubMed record PMID 42119693
- Curated reference (PACVS Evidence Map) Yale: vWF normalised 3/3 NAC vs 0/6 controls (p=0.0119); primary mechanism is lipid metabolism restoration (beta-oxidation protection) not spike protePACVS Evidence Map
Mechanism and notes
Recorded mechanism or class: Anti-inflammatory; Immunomodulatory; Neurological / Autonomic.
Clinical notes: NAC 600-1800mg/day. Glutathione/antioxidant support; studied for fatigue/oxidative stress in Long COVID/ME-CFS. Good safety profile; small positive studies.
Safety: Excellent safety profile. GI upset (nausea, vomiting, diarrhea) at high doses. Rare bronchospasm with inhalation. Safe in pregnancy at standard doses.
Dosing in studies: 600–1800 mg/day divided doses (e.g. 600 mg TID); durations in studies 4–12 weeks.
Frequently asked questions
Is N-Acetylcysteine (NAC) approved for ME/CFS?
N-Acetylcysteine (NAC) is tracked by OSMF as an investigational option for ME/CFS; no regulator has approved it for this indication, and most post-viral conditions have no approved disease-modifying therapy at all. Approval status for the specific indication should always be confirmed with the relevant regulator and prescribing information.
Is N-Acetylcysteine (NAC) in clinical trials for ME/CFS?
ClinicalTrials.gov lists 3 registered trials linking N-Acetylcysteine (NAC) to ME/CFS: 1 is active or not yet recruiting; 2 are terminated, withdrawn, suspended or of unknown status. The most advanced is Phase 2 (NCT04542161, sponsored by Weill Medical College of Cornell University). The largest enrolment is 200 participants (NCT03502044). Registration activity spans 2010 to 2020.
What does the evidence show for N-Acetylcysteine (NAC) in ME/CFS?
Trials of N-Acetylcysteine (NAC) in ME/CFS are registered but none has completed, so there is no outcome evidence from those studies yet; the record is a signal of research interest. OSMF's existing evidence tier for this pair is B (Moderate), taken from the OSMF therapeutic agent database, which grades agents by the volume and design of condition-specific evidence rather than by effect size.
Cite this page
Data: ClinicalTrials.gov, PubMed, Open Targets, ChEMBL, DGIdb and the OSMF therapeutic agent database. Last updated 2026-10-07. Page built 2026-10-07.