Docusate is the common chemical and pharmaceutical name of the anion bis(2-ethylhexyl) sulfosuccinate, also commonly called dioctyl sulfosuccinate (DOSS).

Salts of this anion, especially docusate sodium, are widely used in medicine as an emollient laxative and as stool softeners, by mouth or rectally. Some studies state that docusate is not more effective than a placebo for improving constipation. Other docusate salts with medical use include those of calcium and potassium. Docusate salts are also used as food additives, emulsifiers, dispersants, and wetting agents, among other uses.

It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 148th most commonly prescribed medication in the United States, with more than 3 million prescriptions. In 2023, the combination with senna was the 242nd most commonly prescribed medication in the United States, with more than 1 million prescriptions.

Sodium docusate was patented in 1937 by Coleman R. Caryl and Alphons O. Jaeger for American Cyanamid, which commercialized it for many years as a detergent under the brand name Aerosol OT.

Its use for the treatment of constipation was first proposed in 1955 by James L. Wilson and David G. Dickinson, and quickly popularized under the name Doxinate.

The main medical use of docusate sodium is to treat constipation, acting as a laxative and stool softener. In painful anorectal conditions such as hemorrhoid and anal fissures, it can help avoid pain caused by straining during bowel movements.^{[citation needed]}

When administered by mouth, a bowel movement often occurs in 1 to 3 days, while rectal use may be effective within 20 minutes.

Sodium docusate is sometimes used as a stool softener for children.