NAC may help if you have a mental health disorder

N-acetylcysteine (NAC) is a supplement with promising results as a complementary treatment for trichotillomania and some psychiatric symptoms, but it does not replace medication and has not been consistently proven for addictions. The evidence is mixed and any use should be discussed with a healthcare professional.

N-acetylcysteine, known as NAC, is a compound the body uses to produce glutathione, a key molecule against oxidative stress. In recent years it has moved from the pharmacy aisle to psychiatric research. The reason: it acts on the glutamatergic system through the cystine-glutamate antiporter, known as the xC− system, which places it in brain circuits related to emotional regulation, reward processing and behavioural control.

## What has been studied in psychiatric disorders

Glutamate dysregulation has been implicated in symptoms such as compulsive behaviours, intrusive thoughts, addictive cravings, mood instability and cognitive impairment. That is where interest in NAC fits in.

In schizophrenia, some randomised controlled trials have reported improvements in negative symptoms — reduced motivation, social withdrawal and diminished emotional expression — when NAC was added to standard antipsychotic treatment. In bipolar disorder, early clinical studies suggested improvements in depressive symptoms and functional outcomes, although later and larger studies have produced inconsistent results.

## The strongest data: trichotillomania

The most striking result appears in trichotillomania, compulsive hair pulling. A randomised, placebo-controlled study involving **50 adults** with this disorder found that approximately **56%** of those who received NAC experienced substantial clinical improvement, compared with **16%** of the placebo group, after **12 weeks** of treatment.

For obsessive-compulsive behaviours and addictive disorders the findings are less solid. Larger trials and meta-analyses have not consistently shown significant reductions in cravings or substance use. Most psychiatric studies have investigated NAC over periods of **8 to 24 weeks**, and gastrointestinal discomfort is one of the most frequently reported adverse effects.

## An established hospital use and one that is not

NAC has an established medical use that does not depend on this research: it is a glutathione precursor and is used in hospitals for paracetamol overdose. It is also used to clear the respiratory system. That does not make it a validated psychiatric treatment.

In Spain it is sold as a prescription medicine, and its price and pharmacy availability vary. Buying it online without medical oversight adds risks that do not appear in clinical trials. And it is wise to be sceptical of improvements attributed to NAC in conditions such as dementia based on a relative's observation: there is no established evidence supporting that causal link.

Based on the available research, NAC emerges as a complementary treatment, not a substitute for established psychiatric medications. Any decision about its use belongs to a healthcare professional.