Q: I’ve been a nail-biter since I was a kid. The only way I had nice nails was to spend a fortune at a salon.
When I learned that NAC (N-acetylcysteine) is known to help with BFRBs, body-focused repetitive behaviors, such as nail-biting, hair-pulling or skin-picking, I decided to try it. After a few months of taking this supplement, I had beautiful, natural fingernails for the first time in my entire life. A most welcome extra benefit of NAC for me is that I have absolutely no desire for alcohol and my appetite and craving for unhealthy foods are just gone.
My primary care doc is fairly progressive, but he knew nothing about NAC other than its use in the emergency room to reverse acetaminophen overdose. He gave me the stamp of approval after seeing the changes in me. I take several supplements, but this one has had the most profound and positive change in my overall health.
A: Thank you so much for a fascinating testimonial. As your doctor told you, NAC is “the mainstay of therapy for acetaminophen toxicity” (StatPearls, Feb. 19, 2023). The Food and Drug Administration approved it for this indication in 1985.
There is far less research on its use to control body-focused repetitive behaviors with a compulsive component, such as nail-biting or hair-pulling. A review of the research noted that only a few clinical trials of NAC for this purpose have been conducted (International Journal of Environmental Research and Public Health, May 2022).
We haven’t seen any studies showing that NAC can reduce the urge for alcohol or junk food. However, a small study in Indonesia demonstrated that it helped men stop smoking (Cureus, Feb. 16, 2024).
NAC has a good safety profile. It may cause nausea, vomiting or diarrhea, and occasionally people develop reactions such as a rash or flushing. Headache, hives or fever may occur at the high doses used to treat acetaminophen toxicity (American Family Physician, Aug. 1, 2009).
Q: My 16-year-old daughter had terrible acne. She gave up sugar, dairy and gluten, and her acne disappeared within six weeks. She has beautiful skin now.
A: It sounds like your daughter found a great solution. Studies show that avoiding milk and other dairy products can be helpful for those with acne (Nutrients, Oct. 17, 2023). It also makes sense to avoid sugar-sweetened beverages (European Journal of Endocrinology, Jan. 3, 2024).
Others who would like to learn more about this approach can find further details along with information on medications in our “eGuide to Acne Solutions.” This online resource is located under the Health eGuides tab at PeoplesPharmacy.com.
Q: I have a question about the amount of elemental zinc that would be safe to take per day. My supplement has 7 milligrams of elemental zinc per tablet. When I looked it up, the American Academy of Family Physicians says that the tolerable upper limit of elemental zinc per day is 40 milligrams. How much zinc could I take without interfering with copper?
A: The Recommended Dietary Allowance for adults is 8 milligrams for women and 11 milligrams for men. Your question is sophisticated. Excess zinc intake, which might occur at doses of 50 milligrams/day for weeks, can interfere with copper absorption and reduce immune function. The Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine has established 40 milligrams daily as the tolerable upper limit of zinc for adults.