White horehound plant is a perennial herb cultivated and gathered around the world for its medicinal properties. The plant is a member of the family Lamiaceae, also known as the mint family, which includes other well-known herbs such as rosemary, lavender and thyme. Unlike most herbs in this family, white horehound is relatively non-aromatic.
White horehound was used extensively by the ancient Egyptians and Romans for medicinal purposes. It was included in the United States Pharmacopeia until the year 1900, and used in over-the-counter cough medicines until 1989. In 1990, Germany's Commission E endorsed the use of the herb for treating coughs, colds and indigestion. Today, white horehound is still used by herbalists around the world for treating a variety of ailments.
The white horehound plant has a bushy, compact growth habit and can reach up to 12 inches in height. The plant's leaves are covered in tiny white hairs, which give them a woolly appearance. The foliage has a distinct musky smell that dissipates when dried. Horehounds flower from June to September and appear in crowded whorls. The ten-toothed calyx, or group of sepals, differentiate the plant from other species of horehound.
White horehound is native to northern Africa, southern Europe and the western and central parts of Asia. It has naturalized in many parts of North America. The herb spreads quickly and grows most commonly along roadsides, in ditches and in abandoned waste sites. White horehound is also cultivated in gardens for medicinal and culinary use.
The white horehound plant grows best in poor, dry soil with good drainage in areas that receive full sun. It is a hardy herb that is easy to grow, as it doesn't require much attention. The plant is commonly grown from seed, which should be started indoors six to eight weeks before the last frost date. Seedlings are placed outdoors in rows about 9 inches apart for the best results. No further care is required aside from removing weeds that may compete with the plant for nutrients.
Traditionally, the white horehound plant has been used medicinally to treat asthma, bronchitis, coughs and colds, sore throat and irritation of the skin. Preparations of horehound are widely used for treating respiratory and lung problems. Other medicinal uses of the herb include treating constipation, water retention, gastric ailments and external wounds. Horehound is also used as a flavoring in candy and cough drops.
Although white horehound is generally safe for children and adults, large doses of the herb can cause diarrhea and nausea. Ingesting more than 10 grams of the herb in a 24 hour period may disturb the heart rhythm and the juice of the leaves may irritate sensitive skin. Always consult a physician before consuming horehound or any other herb to make sure it's safe.