Summary
N-acetylcysteine (NAC) has reached Preclinical as its most advanced recorded development stage across any indication, and the database holds no approval for Long COVID / Post-Acute COVID Sequelae (PACVS). No registered clinical trial in this database tests N-acetylcysteine (NAC) specifically in Long COVID / Post-Acute COVID Sequelae (PACVS). The evidence below comes from published literature only, so any clinical signal has not yet been tested prospectively against this condition in a registered study. The literature layer holds 7 publications for this pair: 1 Cochrane review, 3 meta-analyses and 3 clinical trial publications. Publication years run from 2021 to 2025. Because at least one synthesis-level source exists (systematic review, meta-analysis or Cochrane review), this pair has been assessed beyond single studies, although the synthesis may concern a different indication.
The RepurpOS disease-intelligence file for Post-Acute COVID/Vaccination Syndrome ranks 675 candidate therapeutics from Open Targets, ChEMBL, DGIdb and PubMed; only a minority carry direct clinical evidence, and this page covers one of those. Spontaneous remission context recorded for the condition: Spontaneous resolution at 12 months: ~50-70% of patients; persistent symptoms at 2 years in 30-50%; severely debilitating long COVID in 10-15% at 1 year without intervention.
Evidence table
| Evidence tier | C · Preliminary |
|---|---|
| Evidence score | 28.0 (trials 0.0, literature 23.0, tier 5, approved bonus 0.0) |
| Registered trials | 0 total: 0 recruiting, 0 active / not yet recruiting, 0 completed, 0 other |
| Linked publications | 7 (3 meta-analyses, 3 clinical trial publications, 1 Cochrane review) |
| Agent type | Supplement |
| Development stage (any indication) | Preclinical |
| Mechanism / class | Metabolic modulation as a therapeutic strategy for post-acute vaccination syndrome (PACVS) · Halma M, Varon J · 2025 |
| Data sources | OSMF Chronic Disease Review |
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trial scores by status (recruiting / active / enrolling 3, completed 2.5, not yet recruiting 2, unknown 1, terminated / withdrawn / suspended 0.5) plus a phase bonus (phase 3-4 +2, phase 2 +1, phase 1 +0.5).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
No registered trial links N-acetylcysteine (NAC) to Long COVID / Post-Acute COVID Sequelae (PACVS) in the current OSMF trial extract.
Published literature
- Cochrane review Effect of N-Acetylcysteine on mortality in COVID-19 patients: A systematic review and meta-analysis of randomized controlled trialsKow CS, Ramachandram DS, Hasan SS et al. · Inflammopharmacology · 2025 · PMID 40728675
- Meta-analysis COVID-19 clinical outcomes and N-acetylcysteine (CoViNAC study): a GRADE compliant meta-analysis of randomized controlled trials with molecular docking and dynamics simulation studies with Mpro of SARS-CoV-2Varikasuvu SR, Manne M, Kumar S et al. · Cellular and molecular biology (Noisy-le-Grand, France) · 2025 · PMID 40418545
- Clinical trial publication Response to Intravenous N-Acetylcysteine Supplementation in Critically Ill Patients with COVID-19Gamarra-Morales Y, Herrera-Quintana L, Molina-López J et al. · Nutrients · 2023 · PMID 37405379
- Clinical trial publication Evaluation the efficacy and safety of N-acetylcysteine inhalation spray in controlling the symptoms of patients with COVID-19: An open-label randomized controlled clinical trialPanahi Y, Ghanei M, Rahimi M et al. · Journal of medical virology · 2023 · PMID 36495185
- Meta-analysis Is N -acetylcysteine effective in treating patients with coronavirus disease 2019? A meta-analysisChen CH, Hung KF, Huang CY et al. · Journal of the Chinese Medical Association : JCMA · 2023 · PMID 36728396
- Meta-analysis N-acetylcysteine efficacy in patients hospitalized with COVID-19 pneumonia: a systematic review and meta-analysisParaskevas T, Kantanis A, Karalis I et al. · Romanian journal of internal medicine = Revue roumaine de medecine interne · 2023 · PMID 36627753
- Clinical trial publication A pilot study on intravenous N-Acetylcysteine treatment in patients with mild-to-moderate COVID19-associated acute respiratory distress syndromeTaher A, Lashgari M, Sedighi L et al. · Pharmacological reports : PR · 2021 · PMID 34114174
Mechanism and notes
Recorded mechanism or class: Metabolic modulation as a therapeutic strategy for post-acute vaccination syndrome (PACVS) · Halma M, Varon J · 2025.
OSMF's existing evidence tier for this pair is C (Preliminary), derived from the strength of the disease association recorded in OSMF Chronic Disease Review. The tier describes how well the drug-disease link is documented, not how well the drug works.
Frequently asked questions
Is N-acetylcysteine (NAC) approved for Long COVID / Post-Acute COVID Sequelae (PACVS)?
N-acetylcysteine (NAC) has reached Preclinical as its most advanced recorded development stage across any indication, and the database holds no approval for Long COVID / Post-Acute COVID Sequelae (PACVS). 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 Long COVID / Post-Acute COVID Sequelae (PACVS)?
No registered clinical trial in this database tests N-acetylcysteine (NAC) specifically in Long COVID / Post-Acute COVID Sequelae (PACVS). The evidence below comes from published literature only, so any clinical signal has not yet been tested prospectively against this condition in a registered study.
What does the evidence show for N-acetylcysteine (NAC) in Long COVID / Post-Acute COVID Sequelae (PACVS)?
Synthesis-level literature links N-acetylcysteine (NAC) to Long COVID / Post-Acute COVID Sequelae (PACVS), but no registered trial in this database tests the pair, so the evidence is observational, pooled from other indications, or pre-dates registry practice. OSMF's existing evidence tier for this pair is C (Preliminary), derived from the strength of the disease association recorded in OSMF Chronic Disease Review. The tier describes how well the drug-disease link is documented, not how well the drug works.
Cite this page
Data: ClinicalTrials.gov, PubMed, Open Targets, ChEMBL, DGIdb and the OSMF therapeutic agent database. Last updated 2026-07-05. Page built 2026-10-07.