Horehound is the bitter herb *Marrubium vulgare*. People take it as a digestive bitter before meals to encourage healthy digestion. It also appears in old-fashioned cough drops and syrups, though strong modern proof for that use is lacking.
Common forms include a tea made from 1 to 2 teaspoons of dried herb per cup and liquid extracts. The bitterness itself is thought to get digestive juices flowing.
**Key cautions:** Horehound may affect blood sugar and blood pressure. This could interfere with diabetes or blood pressure medications. Do not use it while pregnant or breastfeeding.