Lavoltidine (INN, USAN, BAN; previously known as loxtidine; development code AH-23,844) is a highly potent and selective H<sub>2</sub> receptor antagonist which was under development by Glaxo Wellcome (now GlaxoSmithKline) as a treatment for gastroesophageal reflux disease but was discontinued due to the discovery that it produced gastric carcinoid tumors in rodents.