NAC for Trichotillomania: What the Studies Say

If you’ve searched for help with hair pulling, you’ve probably come across NAC. It turns up in forums, videos and supplement shops, sometimes described as the thing that finally worked. Some people with trichotillomania (trich) do find it helps. Others notice nothing.

This guide sets out what the research actually found, in adults and in children, what’s known about safety, and what to ask a doctor or pharmacist before you try it. It doesn’t give doses. That’s a conversation to have with someone who knows your health and any other medicines you take.

What is NAC?

NAC, short for N-acetylcysteine, is a form of cysteine, one of the building blocks of protein. It works as an antioxidant in the body. It’s sold as a supplement in many countries, and doctors also use it as a medicine, for example to treat paracetamol poisoning and to loosen thick mucus in some lung conditions.

In the US, the Food and Drug Administration (FDA, the body that regulates medicines and food) approved NAC as a drug before it was ever sold as a supplement. That technically keeps it out of the legal definition of a supplement there. Since August 2022, the FDA has said it won’t act against most NAC products sold as supplements while it reviews the issue.

For trichotillomania, NAC is used “off label”. That means using something for a condition it isn’t officially approved for. Doctors sometimes do this when research suggests a benefit, but it’s worth knowing that the evidence for trich is still limited.

How might NAC help with hair pulling?

Researchers tested NAC because it affects glutamate, a chemical messenger in the brain involved in urges and repeated behaviours. The idea is that adjusting the glutamate system might make urges easier to resist. The team behind the first trial suggested this approach could be useful for a range of compulsive behaviours, not just hair pulling.

It’s important to be clear about what this is: a theory that explains why scientists were interested, not a settled explanation. Nobody yet knows exactly why NAC seems to help some adults and not others.

What do the studies show in adults?

One well-run trial in adults found a clear benefit. In 2009, researchers gave 50 adults with trichotillomania either NAC or a dummy pill (a placebo) for 12 weeks. Neither the participants nor the researchers knew who was taking what. By the end, 56% of those on NAC were rated much or very much improved, compared with 16% on the dummy pill. No side effects were reported in the NAC group.

What the trial did and didn’t tell us:

• It was small. Fifty people is enough to show an effect, but not enough to be sure how big it is.
• Most participants were women: 45 of the 50, so there’s much less data on men.
• It was short. Twelve weeks tells us about early change, not about what happens over a year or more.
• It hasn’t been repeated yet. When a 2021 Cochrane review (a review that gathers and weighs all the good-quality trials on a question) looked at all medicine trials for trich, this was still the only placebo-controlled trial of NAC in adults.

Reviews read this evidence slightly differently. The 2021 Cochrane review called the adult result moderate certainty but said there wasn’t enough evidence overall to confirm or rule out any medicine for trich. A 2026 review of around 30 trials was more positive: it counted NAC among the three treatments with the strongest support, alongside two forms of behaviour therapy based on habit reversal.

The fair summary is this. NAC showed a real benefit for many adults in one good trial, it’s promising, and more research is needed.

What do the studies show in children and teenagers?

In children and teenagers, NAC did no better than a dummy pill. A 2013 trial gave 39 young people aged 8 to 17 either NAC or a placebo for 12 weeks, on top of any other help they were already getting. There was no meaningful difference on any measure: 25% improved on NAC and 21% on the placebo.

The researchers concluded that behavioural therapy should be the starting point for children who pull. One child stopped taking NAC because of a body-wide rash, which cleared once they stopped.

Why the difference from adults isn’t known. It may be that trich works differently at different ages, or that one small trial in each group isn’t enough to tell. Either way, the evidence doesn’t support giving NAC to children without a doctor’s advice.

If you’re a parent of a child who pulls, our guide to trichotillomania in children covers what helps at home.

Is NAC safe?

NAC is usually well tolerated, but it isn’t free of side effects, and some people shouldn’t take it. This is why it’s worth talking to a doctor or pharmacist first, even though you can buy it without a prescription in many places.

These points come from patient information on NAC published by Memorial Sloan Kettering Cancer Center, a major US cancer hospital. In the trich trials themselves, side effects were few and mostly mild.

Also check with a doctor before taking NAC if you have asthma, if you’re pregnant, trying for a baby or breastfeeding, or if you take any regular medicine or other supplements.

Should I talk to a doctor before taking NAC?

Yes. Speak to a doctor or pharmacist before you start, and tell them it’s for hair pulling.

Your GP or a local pharmacist is a good place to start. You don’t need to be seeing anyone else for your pulling first.

Questions worth asking:

• Is NAC safe with my other medicines and health conditions?
• What amount and form would suit me, and where should I get it?
• How long should I try it before we decide whether it’s working?
• What side effects should make me stop?
• Would it make sense to try it alongside therapy?

If your doctor hasn’t come across trichotillomania before, you’re not alone. Taking a printout of the studies in this article’s references can help the conversation.

How does NAC compare with therapy?

Therapy has more research behind it. Behaviour therapy based on Habit Reversal Training (HRT), which teaches you to notice when you’re about to pull and to do something else with your hands instead, has been tested in many more trials than NAC. You can read how it works in our guide to Habit Reversal Training.

The two aren’t either/or. For adults, NAC is best thought of as a possible extra, used alongside therapy or practical skills and with a doctor involved. Our complete guide to trichotillomania sums up the evidence on medicines and supplements in one place. For a side-by-side look at every option and the evidence behind each, see our guide to trichotillomania treatment. Our guide to medication for trichotillomania covers prescription medicines doctors sometimes use.

When should I get help?

Get support if pulling is upsetting you, taking up a lot of time, or affecting your work, school or relationships. You don’t have to wait until it’s “bad enough”, and you don’t have to try supplements first.

Many doctors and therapists have never worked with someone who pulls. Everyone in our directory has told us they understand trichotillomania and already help people who pull, in person or online. You can search the directory to find someone who understands hair pulling. Our guide to finding someone who understands trich explains what to ask on a first call.

If you’re a parent looking into this for your child, start with The Parent’s Guide to Trichotillomania: understanding what your child is going through.

Questions people ask

Sources

1. Grant, J.E., Odlaug, B.L. & Kim, S.W. (2009). N-acetylcysteine, a glutamate modulator, in the treatment of trichotillomania: a double-blind, placebo-controlled study. Archives of General Psychiatry, 66(7), 756–763.
2. Bloch, M.H., Panza, K.E., Grant, J.E., Pittenger, C. & Leckman, J.F. (2013). N-Acetylcysteine in the treatment of pediatric trichotillomania: a randomized, double-blind, placebo-controlled add-on trial. Journal of the American Academy of Child & Adolescent Psychiatry, 52(3), 231–240.
3. Hoffman, Williams, Rothbart, Ipser, Fineberg, Chamberlain & Stein (2021). Pharmacotherapy for trichotillomania. Cochrane Database of Systematic Reviews.
4. Fisak, B., Shorb, C., Patel, D. & Ezcurra, V. (2026). The efficacy of psychotherapeutic and pharmacological interventions for trichotillomania: A review and meta-analysis. Journal of Psychiatric Research, 197, 264–274.
5. Healio (2016). N-acetylcysteine effective for skin-picking disorder. Report of Grant et al., randomised trial in excoriation disorder.
6. Memorial Sloan Kettering Cancer Center. N-Acetylcysteine (About Herbs, Botanicals and Other Products).
7. US Food and Drug Administration (2022). FDA releases final guidance on enforcement discretion for certain NAC products.