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Overview: Horse chestnut is a plant called Aesculus hippocastanum. Dietary supplements made from horse chestnut seeds are available over the counter. People usually take horse chestnut for reasons related to blood flow in the veins, but its benefits are not well defined. Common side effects may include headache, itching, nausea, or upset stomach. Before taking horse chestnut, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is horse chestnut used for?

Horse chestnut (Aesculus hippocastanum) is used for various problems related to blood flow, although its benefits are not well defined. Some common uses for horse chestnut include the following.

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

How does horse chestnut work (mechanism of action)?

Horse chestnut is the seed (nut) from the plant Aesculus hippocastanum. It is sometimes called Spanish chestnut.

Horse chestnut contains escin, which is a mixture of multiple chemicals that have effects in the body. Escin (or aescin) can reduce inflammation (swelling). It also seems to strengthen blood vessel walls, making them less “leaky.” This may help to reduce swelling (edema) and other symptoms in people with poor blood flow to the legs. But it is not clear if horse chestnut is better than other options for this condition, such as compression stockings. Most of the research on horse chestnut has used dietary supplements that are taken by mouth. Although some horse chestnut products are applied to the skin, the benefits of these products are unclear.

The effects of escin are also thought to help with hemorrhoids and swollen veins in the legs or scrotum. But the benefits of horse chestnut for these uses are not well defined.

Herbal products, like horse chestnut, naturally contain many different chemicals, such as escin. The amounts of each chemical in a specific horse chestnut product may vary. Different amounts of escin may change the effects of horse chestnut on the body. Some horse chestnut dietary supplements are made to contain a certain amount of this substance.

How should I store horse chestnut?

You should store horse chestnut 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 horse chestnut?

The most common side effects of horse chestnut are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.

  • Headache
  • Itching
  • Nausea or vomiting
  • Upset stomach

There may be other side effects of horse chestnut 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 horse chestnut?

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

Severe Allergic Reactions. Horse chestnut may cause allergic reactions, which can be serious. Stop taking horse chestnut 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 horse chestnut?

Allergies to Ingredients. People who are allergic to any of the following should not take horse chestnut.

  • Aescin
  • Aesculus hippocastanum
  • Escin
  • Horse chestnut
  • Spanish chestnut
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific horse chestnut products they stock.

What should I know about horse chestnut before using it?

Horse chestnut 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 horse chestnut out of the reach of children.

Herbal products, such as horse chestnut, naturally contain many different chemicals. The amount of each chemical in a specific horse chestnut 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 that the plant was processed after it was 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.

Horse chestnut dietary supplements are usually made from the seed (nut) of the plant. All parts of this plant, including the seeds, bark, leaves, and flowers, contain a harmful chemical that can cause serious health problems. This harmful chemical has been removed from extracts of horse chestnut seed. It is important to read the product label to confirm that it contains horse chestnut seed extract. 

The FDA has not tested horse chestnut 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 horse chestnut?

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 whether horse chestnut 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 any of the following.

Other Medicines and Supplements. Horse chestnut may interact with other medicines and supplements. Before taking horse chestnut, 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 horse chestnut could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant.

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

Interactions

Does horse chestnut interact with foods or drinks?

There are no known interactions between horse chestnut and foods or drinks.

It is unknown if drinking alcohol will affect horse chestnut.

Does horse chestnut interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

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

Overdose/Missed Dose

What should I do if I accidentally use too much horse chestnut?

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

Dietary supplements made from horse chestnut usually contain an extract of horse chestnut seed. This extract has been processed to remove a harmful chemical that is naturally found in the seed. Read the product label closely and speak with a health care provider about how to take horse chestnut safely. Do not take double or extra doses, even if you miss a dose.