Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain horse chestnut seed extract. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacists or health care providers before starting.

Scientists have studied horse chestnut seed extract for the following health problem:

Chronic venous insufficiency

Horse chestnut seed extract is most studied for a condition called chronic venous insufficiency. This term is more common in Europe than the United States. It describes several different problems that may be caused by the failure of lower leg veins to work correctly. These problems include leg swelling (edema), pain, itching, varicose veins, breakdown of skin and skin ulcers. Multiple studies suggest that horse chestnut seed extract may help these problems, possibly as well as other treatments, such as compression stockings. However, these studies are small, low quality and not fully convincing. Better research is necessary to provide a clear answer. If you experience sudden leg swelling, consult your health care provider immediately.

Horse chestnut seed extract has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult with a health care provider before using horse chestnut seed extract for any unproven use.

Antiangiogenic
Blood clots
Bruising
Cough
Diarrhea
Dizziness
Fever
Fluid in the lungs (pulmonary edema)
Gallbladder disease
Hemorrhoids
Kidney disease
Liver disease

Menstrual cramps
Nerve pain (neuropathy)
Nighttime leg cramps
Osteoarthritis
Pancreatitis
Prostate enlargement (benign prostatic hypertrophy)
Rectal irritation
Rheumatoid arthritis
Ringing in the ears (tinnitus)
Stomach ulcers
Varicose leg ulcers
Whooping cough (pertussis)

People with known allergies to horse chestnut or any of the chemicals found in horse chestnut (such as esculin, flavonoids, biosides, triosides of quercitins and oligosaccharides, including 1-ketose or 2-ketose) should avoid using horse chestnut seed extract products. Allergic skin rashes (contact dermatitis) have been reported after the use of a skin cream containing horse chestnut seed extract. Intravenous or injected horse chestnut seed extract may cause anaphylactic shock (a severe allergic reaction) or other serious reactions and should be avoided.

Few side effects have been reported from horse chestnut seed extract when taken by mouth at recommended doses. The most common problems are upset stomach and muscle spasms. Less common side effects are headache, skin rash, dizziness, liver problems and kidney problems. Based on animal studies, horse chestnut seed extract may lower blood sugar levels. In theory, horse chestnut seed extract may increase the risk of bleeding. You may need to stop taking horse chestnut seed extract before some surgeries; discuss this with your health care provider. Horse chestnut seed extract should not be used as an injection because it may cause serious side effects. Also avoid using other forms of horse chestnut, such as the flower, branch bark, leaf or raw seeds, because of possible serious side effects or death if eaten.

Several studies report the development of psuedolupus (a syndrome characterized by recurrent fever, muscle pain, and lung and heart muscle inflammation) in patients taking Venocuran or Venopyronum containing phenopyrazone, horse chestnut extract, and cardiac glycosides. Because these are combination products, these effects cannot be blamed on horse chestnut alone.

Horse chestnut seed extract cannot be recommended for use during pregnancy or breast-feeding because of limited safety data. Although no adverse effects were reported in a study of 52 pregnant women taking horse chestnut seed extract for two weeks, more studies are needed before safety can be established.

Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care provider or pharmacist before using herbs or dietary supplements.

Although no adverse drug interactions have been reported, horse chestnut seed extract may theoretically increase the risk of bleeding when used with anticoagulants or antiplatelet drugs. Examples include warfarin (Coumadin), heparin and clopidogrel (Plavix). Some pain relievers may also increase the risk of bleeding if used with horse chestnut seed extract, such as aspirin, ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve, Anaprox). Based on animal research, horse chestnut seed extract may lower blood sugar levels. Caution is advised if you are also taking drugs that may lower blood sugar levels. Patients taking oral drugs for diabetes or using insulin should be monitored closely by their health care provider while using horse chestnut seed extract. Dosing adjustments may be necessary. Because of its effects on how drugs are carried in the blood, horse chestnut seed extract may increase the side effects associated with "protein-bound" drugs, such as amiodarone (Cordarone) and phenytoin (Dilantin). The risk of an interaction with these drugs is theoretical and has not been shown in humans.

In theory, horse chestnut seed extract may increase the risk of bleeding when taken with other products that are also believed to increase the risk of bleeding. Examples include Ginkgo biloba and garlic (Allium sativum). Based on animal studies, horse chestnut seed extract may lower blood sugar levels. People using other herbs or supplements that may alter blood sugar levels, such as bitter melon (Momordica charantia), should be monitored closely by their health care provider while using horse chestnut seed extract. Dosing adjustments may be necessary.

The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care provider before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

One small study concluded that there is no difference between the absorption rates for the retarded versus nonretarded preparation and that daytime absorption was slightly better than nighttime absorption.

Adults (Aged 18 Or Older)

Horse chestnut seed extract: A dose of 300 milligrams every 12 hours, for up to 12 weeks (containing 50 to 75 milligrams of escin per dose), has been taken by mouth. A dose of 600 milligram of chestnut seed extract per day has also been studied.

Children (Younger Than 18)

Horse chestnut seed extract should not be given to children because of a lack of research. Death has occurred when children have eaten raw horse chestnut seeds or tea made from horse chestnut leaves and twigs.

Although horse chestnut seed extract has been suggested for many conditions, the most promising use supported by science is the treatment of chronic venous insufficiency. Evidence does not support the use of horse chestnut seed extract for other health problems. Horse chestnut seed extract should be avoided by pregnant or breast-feeding women and by children, and it should be used cautiously by patients taking anticoagulants or drugs that affect blood sugar levels. Horse chestnut seed extract should be used only at recommended doses for up to 12 weeks. Consult your health care provider immediately if you experience side effects.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research

Natural Standard reviewed more than 215 articles to prepare the professional monograph from which this version was created.

Some of the more recent studies are listed below:

Diehm C, Trampisch HJ, Lange S, et al. Comparison of leg compression stocking and oral horse-chestnut seed extract therapy in patients with chronic venous insufficiency. Lancet 1996;347(8997):292-294.
Pittler MH, Ernst E. Horse chestnut seed extract for chronic venous insufficiency. Cochrane Database Syst Rev 2004;(2):CD003230.
Pittler MH, Ernst E. Horse-chestnut seed extract for chronic venous insufficiency: a criteria-based systematic review. Arch Dermatol 1998;134(11):1356-1360.
Popp W, Horak F, Jager S, et al. Horse chestnut (Aesculus hippocastanum) pollen: a frequent cause of allergic sensitization in urban children. Allergy 1992;Aug, 47(4 Pt 2):380-383.
Siebert U, Brach M, Sroczynski G, Berla K. Efficacy, routine effectiveness, and safety of horse chestnut seed extract in the treatment of chronic venous insufficiency: a meta-analysis of randomized controlled trials and large observational studies. Int Angiol 2002;Dec, 21(4):305-315.
Simini B. Horse-chestnut seed extract for chronic venous insufficiency. Lancet 1996;337(9009):1182-1183.
Vayssairat M, Debure C, Maurel A, et al. Horse-chestnut seed extract for chronic venous insufficiency. Lancet 1996;347(9009):1182.