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 milligrams of chestnut seed extract per day has also been studied.
A gel preparation of horse chestnut containing 2% escin (applied to the skin 3-4 times daily) has been studied for bruising, without clear benefits.
There is not enough scientific evidence to recommend use of horse chestnut in children. Deaths have been reported in children who ate raw horse chestnut seeds or tea made from horse chestnut leaves and twigs.
Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Horse chestnut seed extract (HCSE) may cause an allergic reaction in patients with known allergy to horse chestnuts, esculin, or any of its ingredients (flavonoids, biosides, trisides of quertins, and oligosacharides including 1-ketose and 2-ketose). Anaphylactic shock (severe allergic reaction) has been reported with intravenous (through the vein) use.
Allergic skin rashes (contact dermatitis) have been reported after use of a skin cream containing horse chestnut seed extract.
Side Effects and Warnings
Unprocessed horse chestnut seeds have been associated with significant toxicity and death. Symptoms associated with horse chestnut poisoning may include vomiting, diarrhea, headache, confusion, weakness, muscle twitching, poor coordination, coma, or paralysis. Horse chestnut seed extract (HCSE) standardized to escin content should not contain significant levels of esculin and should not have the same risks.
Standardized HCSE is generally considered to be safe in adults at recommended doses for short periods of time. Stomach upset, muscular (calf) spasm, headache, dizziness, nausea, and itching have been reported. Contact skin irritation (dermatitis) has been reported following application of HCSE to the skin.
Based on animal study, HCSE may cause lowered blood sugar. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare provider, and medication adjustments may be necessary.
In theory, horse chestnut may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Monitoring is recommended and dosing adjustments may be necessary. Liver and kidney toxicity has been associated with horse chestnut. Aflatoxins, considered to be cancer-causing agents, have been identified in commercial skin products containing horse chestnut, but not in HCSE.
Several studies report the development of pseudolupus (a syndrome characterized by recurrent fever, muscle pain, and lung and heart muscle inflammation) in patients taking Venocuran or Venopyronum, which contains phenopyrazone, horse chestnut extract, and cardiac glycosides. Because these are combination products, these effects may not be accounted for by horse chestnut alone.
Pregnancy and Breastfeeding
There is not enough scientific research to recommend the safe use of horse chestnut or HCSE during pregnancy and breastfeeding.