N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis.
The NAC evidence pools people with bipolar disorder, depression, hair-pulling and smoking into one number — is there any trial in a population that actually looks like me?
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: Two of the five authors — Berk and Dean — are investigators on trials included in the pooled estimate, so this is not an independent synthesis of other people's work, and Berk's disclosures elsewhere in this literature record consultancy to Bioadvantex, a company commercialising NAC. The search ended in November 2014 and so predates the larger negative bipolar trial listed below. No funding statement was readable, so funding is UNKNOWN.
NAC sits in an unusual place.
Of 38 studies examined, five double-blind placebo-controlled trials met inclusion, giving 574 participants (291 NAC, 283 placebo) followed for 12-24 weeks across mixed diagnoses — two bipolar, one major depression, one trichotillomania, one heavy smoking. NAC improved depressive symptoms with a standardised mean difference of 0.37 (95% CI 0.19 to 0.55, P<0.001) and improved global functioning, with no change in quality of life and only minor adverse events (OR 1.61, 95% CI 1.01 to 2.59). An SMD of 0.37 is a small-to-moderate effect drawn from five heterogeneous trials in five different populations.
Worth asking
The NAC evidence pools people with bipolar disorder, depression, hair-pulling and smoking into one number — is there any trial in a population that actually looks like me?
Source
N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis. — Fernandes BS, Dean OM, Dodd S, Malhi GS, Berk M. (2016)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.4088/JCP.15r09984
DOI: 10.4088/JCP.15r09984
How this was scored
- Study design
- Meta-analysis of randomised trials
- Funding
- Funding not disclosed
- Published in
- Reputable peer-reviewed journal
- Sample size
- 574
- Preregistered
- No
- Conflicts disclosed
- No
- Independent of proponent
- No
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 19, 2026.
Questions
How strong is the evidence behind this?
Resolv rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 61 out of 100 on our published rubric. One caveat travels with that badge: Two of the five authors — Berk and Dean — are investigators on trials included in the pooled estimate, so this is not an independent synthesis of other people's work, and Berk's disclosures elsewhere in this literature record consultancy to Bioadvantex, a company commercialising NAC. The search ended in November 2014 and so predates the larger negative bipolar trial listed below. No funding statement was readable, so funding is UNKNOWN. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis. — Fernandes BS, Dean OM, Dodd S, Malhi GS, Berk M. (2016). Published in: Reputable peer-reviewed journal. DOI: 10.4088/JCP.15r09984. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Meta-analysis of randomised trials. Funding: Funding not disclosed. The researchers were not independent of whoever benefits from the result. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is nac, n-acetylcysteine, n-acetyl-l-cysteine, acetylcysteine, acetadote, mucomyst FDA approved for this use?
No. Its current status is: Not FDA-evaluated for this use. NAC sits in an unusual place.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.