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Overview: White horehound is an herb called Marrubium vulgare. The leaves and flowering tops are most often used to make teas, liquid extracts, and dietary supplements. People take white horehound most often for cough and respiratory conditions, such as sore throat and bronchitis. It is also used to help with an upset stomach. Common side effects include upset stomach. Before taking white horehound, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is white horehound used for?

White horehound (Marrubium vulgare) is most commonly used for respiratory conditions. Benefits are not well defined based on current evidence. Common reasons people take white horehound include.

  • Cough or sore throat
  • Lung or breathing problems
  • Upset stomach

Note: The FDA has not reviewed white horehound for safety and effectiveness. Learn more about dietary supplements here.

How does white horehound work (mechanism of action)?

White horehound is an herb. Its scientific name is Marrubium vulgare. The leaves and other parts of the plant are used in dietary supplements. White horehound has been used in traditional medicine for many centuries, especially for cough and respiratory conditions.

The main active chemical in white horehound is called marrubiin. It is thought to help with coughs by working as an expectorant. An expectorant helps loosen and thin mucus in the airways, making it easier to cough up.

Herbal products, such as white horehound, naturally contain many different chemicals, such as marrubiin. The amounts of each chemical in a specific white horehound product may vary. Different amounts of marrubiin may change the effects of white horehound on the body. Some white horehound dietary supplements are made to contain a certain amount of these substances.

How should I store white horehound?

You should store white horehound according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of white horehound?

White horehound seems to be generally well tolerated. But there is not enough research to know what all the common side effects may be. The most common side effects reported with white horehound are listed below. Tell your health care provider if you have any of these side effects that bother you.

There may be other side effects of white horehound that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of white horehound?

While less common, the most serious side effects of white horehound are described below, along with what to do if they happen.

Severe Allergic Reactions. White horehound may cause allergic reactions, which can be serious. Stop taking white horehound and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use white horehound?

Allergies to Ingredients. People who are allergic to any of the following should not take white horehound.

  • Common horehound
  • Horehound
  • Marrubium vulgare
  • White horehound
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific white horehound products they stock.

What should I know about white horehound before using it?

White horehound is a dietary supplement. It cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep white horehound out of the reach of children.

Herbal products, such as white horehound, naturally contain many different chemicals. The amount of each chemical in a specific white horehound product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year when it was harvested, and the way the plant was processed after being harvested. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.

The FDA has not tested white horehound products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using white horehound?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if white horehound is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have diabetes or problems with blood sugar. Some evidence suggests that plants in the marrubium genus may affect blood sugar levels. This has not been well studied in humans. The American Diabetes Association notes there is not enough evidence to support routine use of herbal supplements for blood sugar control.

Other Medicines and Supplements. Before taking white horehound, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how white horehound could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if white horehound passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does white horehound interact with foods or drinks?

There are no known interactions between white horehound and foods or drinks. It is unknown if drinking alcohol will affect white horehound.

Does white horehound interact with medicines (drug interactions)?

Tell your health care provider about all medicines you are taking before starting white horehound.

The interactions between white horehound and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with white horehound is incomplete. Always check with your health care provider before taking white horehound with any medicines.

Overdose/Missed Dose

What should I do if I accidentally use too much white horehound?

If you or someone else has used too much white horehound, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

White horehound is available over the counter in forms such as teas, liquid extracts, lozenges, and capsules. Doses vary widely by product and intended use. Read the product label closely and speak to a health care provider about how to use white horehound safely. Do not take double or extra doses, even if you miss a dose.