Sufferers feel impelled to pull out their hair and eyelashes
A simple supplement could help treat people with an impulse disorder that manifests in hair-tearing, say experts.
Trichotillomania suffers are blighted by uncontrollable urges to pluck the hair of the scalp and even eyebrows and lashes, often to the point of baldness.
Although seen as a behavioural and psychological problem, scientists are hopeful that the problem could be solved with an amino acid pill.
Archives of General Psychiatry reports promising early trial findings.
A group of 50 people with trichotillomania were asked to take part in a 12-week trial of the pill containing the amino acid N-acetylcysteine.
N-acetylcysteine could be an effective treatment option for people with trichotillomania
The same supplement has shown promise for treating people with compulsive disorders and is thought to work on the glutamate system, the largest nerve signal transmission system in the human brain.
Indeed, some studies suggest that abnormalities in the natural brain chemicals serotonin and dopamine may play a role in trichotillomania, although genes may also be involved.
In the trial, half of the volunteers were given the treatment and the other half a dummy pill.
After 12 weeks, patients taking the active medication had significantly greater reductions in hair-pulling symptoms than those taking placebo.
Overall, 56% of patients were considered to be "much or very much improved" with N-acetylcysteine use compared with 16% taking placebo.
And N-acetylcysteine compared favourably with existing treatment options.
The magnitude of improvement seen in patients taking the amino acid pills was greater than that reported with other medications and was similar to that reported for cognitive behaviour therapy alone or combined with medication, such as antidepressants.
Stress and genetics play a part
Driven by a strong urge or impulse
Ranges in severity - often to the point of baldness
Dr Jon Grant, of the University of Minnesota School of Medicine, and his co-authors, said: "N-acetylcysteine could be an effective treatment option for people with trichotillomania."
But they said the underlying causes of trichotillomania should still be tackled using cognitive behavioural therapy. And more work will be needed to prove that supplements, which can be bought in health shops, do actually work
Trichotillomania may affect up to 5% of the population, although getting a handle on the exact prevalence is difficult, partly because sufferers may hide their condition and be too embarrassed to seek help.
Hair-pulling most commonly begins in the early teens, although it can start at a much younger or older age, and in some cases can be linked to a stressful life event like the death of a family member.
For some, hair-pulling can be seen as a soothing behaviour that is driven by rising tension.
For others, hair-pulling is undertaken during times of relaxation and is a habit that is to some extent subconscious.
Once the hair has been pulled it is often played with or eaten rather than immediately discarded.
Trichotillomania shares some common features with obsessive compulsive disorder, and is probably linked to common genetic factors, but it is not the same condition.