2-hydroxybutyric acid is a hydroxybutyric acid having a single hydroxyl group located at position 2; urinary secretion of 2-hydroxybutyric acid is increased with alcohol ingestion or vigorous physical exercise and is associated with lactic acidosis and ketoacidosis in humans and diabetes in animals. It has a role as a human metabolite and an algal metabolite. It is a hydroxybutyric acid and a 2-hydroxy monocarboxylic acid. It derives from a butyric acid. It is a conjugate acid of a 2-hydroxybutyrate.