DMSA powder  is the organosulfur compound with the formula HO2CCH(SH)CH(SH)CO2H. This colorless solid contains two carboxylic acid and two thiol groups, the latter being responsible for its mildly unpleasant odor. It occurs in two diastereomers, meso, and the chiral dl forms. The meso isomer is used as a chelating agent. The acid is most often used as a treatment for heavy metal toxicity and is a water-soluble and non-toxic substance.

DMSA powder is indicated for the treatment of lead poisoning in children with blood levels measured above 45 µg/dL. The use of DMSA is not approved for prophylactic/prevention of lead poisoning in anticipation of exposure in known lead-contaminated environments. Its elimination
half-life is 2.5-3.5 h. DMSA can cross the blood-brain barrier of mice, but not that of humans, limiting its use to extracting heavy metals from parts of the body other than the central nervous system.

Another application for DMSA is for the provocation of tissue-heavy metals in anticipation of a urine test. This is sometimes called a "challenge" or "provoked" heavy metals test. DMSA is used to help mobilize heavy metals stored in body tissues (and therefore not typically present in the circulation)
and increase the excretion of heavy metals in the urine. In a study by Howard Frumkin et al., this sort of test was shown to not reliably provide an indication of past chronic mercu exposure, something it was often used for. A 2004 study by GP Archbold, et al. called the results of a DMSA
challenge test "misleading" for the purposes of diagnosing mercu toxicity. Moreover, DMSA shares the limitation of extracellular distribution, which makes it unable to cross the cell membrane and chelate heavy metals from intracellular sites.

The relative activities of a series of novel monoalkyl esters of meso-2,3-dimercaptosuccinic acid (DMSA) have been examined as agents for the mobilization of cadm,  owing to the ability of these monoesters to cross cell membranes. The monoesters were found to be more effective than the parent compound DMSA.