NAC, or N-Acetylcysteine is a supplement used to build antioxidants in the body. It has many valid medical uses and may be prescribed by a doctor. There is some data suggesting that it can help reduce the frequency of skin picking in people with dermatillomania. NAC can have serious drug and medical interactions and should be taken under the advice of a physician.
Other natural treatments might include herbal supplements or teas taken for their calming effect, but there is no medical research backing the efficacy of this treatment.