On The Shelf
Johanna Taylor Katroscik, PharmD
White horehound, also known as Marrubium vulgare, is a perennial plant that is part of the mint family. Although there are two other commonly known types of horehound, white horehound is the variety that is most used as an herbal supplement. While horehound may not sound like a familiar supplement, it is often an ingredient used in cough drops, lozenges, and tea blends that are sold to ease sore throats (e.g., Ricola herbal drops).
Background and function
The white horehound plant is native to southern Europe, central and western Asia, and northern Africa. However, like most plants have over the centuries, it has made its way to other continents and can now be found in North America, South America, New Zealand, and Australia.
For hundreds (and some claim thousands) of years, it has been used as a part of folk medicine and as a natural remedy to treat sore throats and coughs. In fact, the first mention of white horehound in written literature dates back to ancient Egypt, where it was used as a mucus expectorant. Currently, it is most commonly commercially available as a tincture, dried leaves (tea), and in cough drops or lozenges. In addition to being commercially available, the plant is often used to make homemade teas, candies, or tinctures.
Is there a benefit?
Traditionally, white horehound has been used to ease a cough or sore throat and is popular as a digestive aid, an appetite stimulant, a treatment for diabetes, and an analgesic.
Almost no in vivo studies have been done to assess efficacy or safety of horehound, but there have been some in vitro and animal studies that have looked at the potential benefits. None of these studies offer any definitive data that supports the use of horehound.
To date, no studies have shown that it is effective in stimulating a person’s appetite; reducing blood sugar; or in relieving a sore throat, cough, or bronchitis. Several small studies suggest that horehound might aid in digestion or be gastroprotective, but these studies have only been done in animals and there is no human data to support this.
Daily requirements and dietary sources
There are no daily recommended requirements, and most products that contain horehound for sore throat state that if the sore throat lasts for longer than one week professional medical attention should be considered.
Because white horehound is a plant, there are no dietary sources of horehound aside from teas that are made from the plant. Patients who are using white horehound as a supplement should not use it for more than a week or two at a time.
What to tell your patients
There are no clinical data to support or oppose the use of white horehound. It is thought to be relatively safe and tolerable. However, there are no data on its use in children, or in pregnant or lactating people, and it is generally recommended to avoid its use in these patient populations.
Horehound may also interact with several medication classes including blood pressure–lowering medications, diuretics, blood sugar–lowering medications, and expectorants. When using horehound with other medications, monitor for potential or suspected interactions. Horehound use should be discontinued if medication interactions are suspected. While horehound may not have a lot of data to support its use, it has been used by many people over the years and does meet the criteria for “traditional use registration” for nonprescription herbal medicines in Europe. ■