Calomel

Calomel was marketed as a purgative agent to relieve congestion and constipation; however, physicians at the time had no idea what the medication’s mechanism of action was. They learned how calomel worked through trial and error. It was observed that small doses of calomel acted as a stimulant, often leading to bowel movements, while larger doses caused sedation. During the 19th century, calomel was used to treat numerous illnesses and diseases like mumps, typhoid fever, and others—especially those that impact the gastrointestinal tract, such as constipation, dysentery, and vomiting. As mercury softened the gums, calomel was the principal constituent of teething powders until the mid-twentieth century. Babies given calomel for teething often suffered from acrodynia.