What Is Horse Chestnut?

This herb is purported to help varicose veins and hemorrhoids

Horse chestnut capsules

Verywell / Anastasia Tretiak

Horse chestnut (Aesculus hippocastanum) is a type of tree that grows throughout the Northern Hemisphere. In herbal and folk medicine, horse chestnut seed, leaves, bark, and flowers have long been used to relieve symptoms, such as swelling and inflammation, and to strengthen blood vessel walls.

Health claims for horse chestnut include the treatment of the following problems:

  • Circulatory disorders
  • Diarrhea
  • Hemorrhoids
  • Varicose veins

Horse chestnut contains a compound called aescin, which has been found to produce an anti-inflammatory effect. The unprocessed seeds, leaves, bark, and flowers also contain esculin, which is poisonous and may increase the risk of bleeding. (Aescin is a different compound and is considered to be safe.) Esculin can be removed Properly processing horse chestnut seed extract removes esculin.

What Is Horse Chestnut Used For?

Horse chestnut has been proven effective for people suffering from chronic venous insufficiency (CVI). CVI is a condition in which the veins don't efficiently return blood from the legs to the heart and is linked to problems like varicose veins, ankle swelling, and nighttime leg cramping. Very little research has been done on horse chestnut for other conditions.

Chronic Venous Insufficiency

Research suggests that horse chestnut seed extract may be useful in treating CVI. In a systematic review of 12 clinical trials published in 2012, for instance, horse chestnut seed extract improved leg pain, swelling, and itching in people with CVI when taken for a short time. Researchers concluded that "the evidence presented suggests that horse chestnut seed extract is an efficacious and safe short‐term treatment for CVI." One trial indicated that horse chestnut may be as effective as treatment with compression stockings. According to the National Center for Complementary and Integrative Health, evidence to support the beneficial impact of horse chestnut on other conditions besides CVI is lacking.

Horse chestnut capsules
Verywell / Anastasia Tretiak

Selection, Preparation, & Storage

Never ingest any part of the horse chestnut tree. Poisoning from the fresh, unprocessed herb—which includes its leaves, bark, or flowers—can lead to sickness.

Instead, buy a commercial supplement. Manufacturers of horse chestnut products remove the toxic component, esculin. These products appear to be safe, as there have been few reports of harmful side effects despite being widely used in Europe.

Most supplements are standardized to contain 20-120 milligrams of aescin. The most common dosage is 50 milligrams of aescin two or three times a day.

To prevent gastrointestinal upset, choose a delayed-release formulation.

Possible Side Effects

Horse chestnut extract may produce a number of adverse effects, including itching, nausea, or gastrointestinal problems, muscle aches, and headache.

In order to ensure the safe use of horse chestnut, make sure to consult your physician if you're considering using the herb to treat CVI or another chronic health condition.

People with kidney or liver disease and bleeding disorders should avoid horse chestnut. Horse chestnut should not be combined with aspirin, Plavix (clopidogrel), Coumadin (warfarin), and other anticoagulant or anti-platelet (blood-thinning) drugs unless under medical supervision as it may increase the effect of these medications.

Keep in mind that supplements haven't been tested for safety and due to the fact that dietary supplements are largely unregulated, the content of some products may differ from what is specified on the product label. Note, too, that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications hasn't been established.

Frequently Asked Questions

  • Is horse chestnut safe for the kidneys?

    Taking horse chestnut supplements in moderate doses should be safe for people with healthy kidneys. However, people with kidney or liver disease should not take horse chestnut. 

  • What does horse chestnut do for your legs?

    Horse chestnut seed extract may help treat chronic venous insufficiency (CVI), a circulation problem linked to varicose veins, ankle swelling, and nighttime leg cramps. Research suggests horse chestnut can reduce leg pain, swelling, and itching in people with CVI.

  • Is horse chestnut poisonous?

    Yes, raw, unprocessed horse chestnut can be deadly. Ingesting unprocessed parts of the horse chestnut tree, including the leaves, bark, or flowers, can lead to sickness and possible poisoning. The horse chestnut tree contains a poisonous chemical known as esculin. Commercial supplements are processed to remove esculin and are safe to consume. 

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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. NIH. National Center for Complimentary and Integrative Health. Horse chestnut.

  2. Dudek-Makuch M, Studzińska-Sroka E. Horse chestnut – efficacy and safety in chronic venous insufficiency: an overview. Rev Bras Farmacogn. 2015;25(5):533-41. doi:10.1016/j.bjp.2015.05.009

  3. Pittler MH, Ernst E. Horse chestnut seed extract for chronic venous insufficiency. Cochrane Database Syst Rev. 2012;11:CD003230. doi:10.1002/14651858.CD003230.pub4

  4. Drugs.com. Horse chestnut.

  5. RxList. Horse chestnut.

Additional Reading
  • NIH. National Center for Complementary and Integrative Health. Horse Chestnut.