Abstract
N-Acetyl-L-cysteine, a thiol drug used commonly as an expectorant, was used to inhibit the growth of L-cystine crystals. Dual effects of a chemical decomposition reaction and crystallization inhibition ensure that N-acetyl-L-cysteine has an unusual inhibitory effect on the growth of L-cystine crystals, and could aid its development as a new drug for the treatment of L-cystine stones.