- Since ancient Egypt, white horehound (Marrubium vulgare L.) has been used as an expectorant (to facilitate removal of mucus from the lungs or throat). Ayurvedic, Native American, and Australian Aboriginal medicines have traditionally used white horehound to treat respiratory (lung) conditions. The U.S. Food and Drug Administration (FDA) banned horehound from cough drops in 1989 due to insufficient evidence supporting its efficacy. However, horehound is currently widely used in Europe, and it can be found in European-made herbal cough remedies sold in the United States (for example, Ricola®).
- There is a lack of well-defined clinical evidence to support any therapeutic use of white horehound. The expert German panel, the Commission E, has approved white horehound for lack of appetite, dyspepsia (heartburn), and as a choleretic. There is promising early evidence favoring the use of white horehound as a hypoglycemic agent for diabetes mellitus and as a non-opioid pain reliever.
- There is limited evidence on the safety or toxicity in humans. White horehound has been reported to cause hypotension (low blood pressure), hypoglycemia (low blood sugar), and arrhythmias (abnormal heart rhythms) in animal studies