Horse chestnut is a tree native to parts of southeastern Europe. It produces spiny-shelled fruits containing seeds, known as conkers, which may possess some health benefits. However, more research is necessary to determine these benefits and potential side effects.

Proponents of horse chestnut suggest that the seed extract contains active compounds that may protect veins and promote blood flow. As such, some people may use it to treat varicose veins. However, while the seed extract appears to be safe for short-term use, raw materials from the horse chestnut may contain toxic compounds. Therefore, more research is necessary to distinguish the possible health benefits and side effects.

This article discusses the properties of horse chestnuts and how they may be beneficial to health conditions. In addition, it examines what the research says and essential considerations for safety and side effects.

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Aesculus hippocastanum, or horse chestnut, is a tree native to parts of southeastern Europe but now grows in many areas around the world. It is also known as buckeye or Spanish chestnut. People may be able to distinguish the tree by its leaves and flowers, but its most notable trait is its fruit. Insects pollinate the flowers, which then develop a glossy red-brown conker inside a spiky green husk.

The tree’s fruits resemble sweet chestnuts but have a bitter taste and are unsafe to eat. However, people have traditionally used horse chestnut extract as herbal medicine to treat several health conditions. The main active component in horse chestnut is escin. Additionally, horse chestnut seeds contain the following chemical compounds:

Research suggests that escin has anti-inflammatory properties and protects the cells lining the veins. This may reduce the leakage of blood plasma and prevent swelling. Additionally, escin may improve the tone of veins and their ability to contract effectively.

Therefore, horse chestnut’s herbal properties suggest it is a potential treatment for conditions that involve inflammation or swelling in the veins.

Chronic venous insufficiency

Chronic venous insufficiency (CVI) occurs when the valves in a person’s veins are unable to work correctly. This results in the veins being less able to transport blood back to the heart. This can lead to a person developing varicose veins.

CVI affects approximately 6–7 million people in the United States, with more females having the condition than males. Symptoms can include swelling, pain, and skin discoloration. If a doctor does not treat CVI, it can lead to venous ulcers or deep vein thrombosis.

As horse chestnut may possess vasoprotective properties, it could potentially improve the tone of veins and help them pump blood back to the heart.

A 2015 review article indicates that horse chestnut seed extract could provide a safe and tolerable treatment option for CVI. Similarly, the European Medicines Agency (EMA) highlights that the extract may relieve symptoms of discomfort and heaviness of the legs associated with CVI.

Hemorrhoids

Due to its beneficial action on veins, some evidence suggests that horse chestnut may be helpful for hemorrhoids. However, there is little clinical research available to support this. Therefore, more research is necessary to determine if horse chestnut extract could be beneficial for treating hemorrhoids.

Potential benefits for male infertility

The National Center for Complementary and Integrative Health (NICCH) reports that scientists have researched horse chestnut seed extract for male infertility associated with varicocele. This is a condition in which the veins inside the scrotum become inflamed. However, more research is still necessary as there is not enough evidence to draw firm conclusions.

Possible anti-inflammatory and hypoglycemic effects

A 2021 animal study indicates that escin present in a type of horse chestnut originating from Uzbekistan may possess anti-inflammatory and hypoglycemic effects.

The researchers suggest that the active ingredients in horse chestnut may have potential uses as pharmaceutical drugs to treat diabetes and inflammation. Furthermore, they note that these compounds might potentially treat thromboembolism, viruses, and even cancer.

Additionally, a 2022 laboratory study indicates that horse chestnut extract might help wound healing or help treat tumors in skin cancer. However, as these are animal or laboratory studies, scientists need to conduct more human research to confirm these results.

According to the NICCH, the raw seeds, bark, flowers, and leaves of horse chestnuts are unsafe due to a toxic component. However, it advises that standardized horse chestnut seed extracts from which manufacturers have removed the toxic element appear safe for short-term use. While there is limited evidence, research also suggests that horse chestnut is unlikely to result in liver injury.

People who are pregnant or breastfeeding should not consume horse chestnut as experts do not know the effects on parents or children. Additionally, there is no data regarding how horse chestnut may affect fertility.

Additionally, the NICCH and the EMA advise that horse chestnut may have the following undesirable effects:

The EMA advises that if people have the following symptoms after taking horse chestnut extract, they should consult a doctor:

  • severe pain
  • sudden swelling of one or both legs
  • inflammation of the skin
  • ulcers
  • cardiac or renal insufficiency

As such, it is advisable for anyone considering horse chestnut to discuss taking this supplement with a healthcare professional.

Horse chestnut is typically available in many formulations, such as capsules, tablets, liquid extract, gels, and solutions. These formulations can vary in strength, and people may need to use them differently depending on their symptoms. Therefore, people should follow instructions on the packaging or ask a healthcare professional for guidelines.

For example, instructions for a horse chestnut pellet to treat hemorrhoid pain advise that people dissolve 5 pellets under their tongue 3 times a day until symptoms cease or as their doctor directs. For a horse chestnut tincture to treat leg pain, guidelines recommend that adults and children above 12 years use 2–5 drops 1–3 times daily in water before meals.

Horse chestnut is a tree that bears spiny-shelled fruits that may possess some health benefits. People can extract the active compounds of horse chestnut from its seeds and leaves. Proponents suggest that horse chestnut extract may protect veins and promote blood flow.

Therefore, it may be beneficial for treating symptoms of CVI, varicose veins, and hemorrhoids. However, more research is necessary to confirm these effects. Additionally, as with any supplement, it is advisable for a person to consult a healthcare professional before taking horse chestnut.