N-acetylcysteine (NAC) is a supplement that may help with various conditions. Possible uses range from improving athletic performance to managing blood sugar levels and treating chronic lung problems.

DEAR DR. ROACH: I’d like to have your thoughts on what value the NAC supplement may have for reducing cravings for marijuana or nicotine? I’m 73 and have been smoking marijuana daily since I was 21.

A supplement found in any drug store’s vitamin aisle could help treat a problem that plagues both children and adults: habitual nail biting. The option could be especially valuable in the era of COVID ...