N-Acetyl Cysteine and Reduced C-Reactive Protein Levels

Research synthesisLow evidenceSmall effect3 studies · 0 beneficial · 3 neutral · 0 harmful

Across 3 studies, all reported neutral effects with small effect sizes. No statistically significant reductions in C-reactive protein (CRP) were observed. The most-studied doses were 600 mg daily and 600 mg twice daily, in populations including older adults with vitamin D deficiency and patients with rheumatoid arthritis. Median study duration was 70 days.

Effective dose range: 600 mg daily to 600 mg twice daily
Studied populations: older adults with vitamin D deficiency, patients with rheumatoid arthritis

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. None of the included studies reached statistical significance, suggesting that any effect is likely negligible. The review noted contradictory findings in the literature on CRP and other biomarkers.

Generated Jul 14, 2026

Doses used in studies

mg/day: 600–1,200 (median 900, IQR 750–1,050) — 2 studies

Time to effect

Median: 10 weeks · IQR 9 weeks–11 weeks · Range 8 weeks–2.8 months — Reported in 2 of 3 studies

3 of 3 papersPopulation:

Co-administration of vitamin D and N-acetylcysteine to modulate immunosenescence in older adults with vitamin D deficiency: a randomized clinical trial.
- 2025-05-12
- RCT
- Frontiers in immunology 16
- - Samira Rastgoo
  - Katayoun Pourvali
  - Seyed Ahmad Raeissadat
  - Ghazaleh Eslamian
  - Hamid Zand
- PubMed: 40421021
- DOI: 10.3389/fimmu.2025.1570441
6 Insights on
- Reduced C-Reactive Protein Levels
- High evidence
- Clinical
No significant differences were observed between the groups in serum ... C-reactive protein (CRP) ... after the intervention.
Effect
Neutral
Effect size
Small
Significant
No
Dose
1000 IU daily
A Pilot Study to Evaluate the Effects of Oral N-Acetyl Cysteine on Inflammatory and Oxidative Stress Biomarkers in Rheumatoid Arthritis.
- 2019-07-31
- RCT · n = 23
- Current rheumatology reviews 15(3)
- - Ghazal Hashemi
  - Mahtabalsadat Mirjalili
  - Zahra Basiri
  - Ahmad Tahamoli-Roudsari
  - Nejat Kheiripour
  - Maryam Shahdoust
  - Akram Ranjbar
  - Maryam Mehrpooya
  - Sara Ataei
- PubMed: 30255760
- DOI: 10.2174/1573403x14666180926100811
10 Insights on
- Reduced C-Reactive Protein Levels
- High evidence
- Clinical
only NO, MDA and TTG showed a significant difference in the NAC group as compared to the placebo group at the end of study
Effect
Neutral
Effect size
Small
Significant
No
Dose
600 mg twice daily
N-Acetyl-L-cysteine in human rheumatoid arthritis and its effects on nitric oxide (NO) and malondialdehyde (MDA): analytical and clinical considerations.
- 2022-07-13
- Review
- Amino acids 54(9)
- - Dimitrios Tsikas
  - Marie Mikuteit
- PubMed: 35829920
- DOI: 10.1007/s00726-022-03185-x
5 Insights on
- Reduced C-Reactive Protein Levels
- Low evidence
Reported data on NO, MDA and clinical parameters, including C-reactive protein, interleukins and tumour necrosis factor α, are contradictory in the literature.
Effect
Neutral
Effect size
Small
Significant
No

N-Acetyl Cysteine and Reduced C-Reactive Protein Levels

Co-administration of vitamin D and N-acetylcysteine to modulate immunosenescence in older adults with vitamin D deficiency: a randomized clinical trial.

A Pilot Study to Evaluate the Effects of Oral N-Acetyl Cysteine on Inflammatory and Oxidative Stress Biomarkers in Rheumatoid Arthritis.

N-Acetyl-L-cysteine in human rheumatoid arthritis and its effects on nitric oxide (NO) and malondialdehyde (MDA): analytical and clinical considerations.