Horse chestnut trees (Aesculus hippocastanum) are recognized by their large, towering trunks and full branches that tout clusters of white flowers with chestnut-like seeds (also known as conkers or buckeyes). The raw seeds, barks, leaves, and flowers should not be ingested as they contain a poison called esculetin that may lead to increased risk of bleeding and DNA damage [1, 2].
Seeds from horse chestnut trees were traditionally used to reduce joint pain, soft tissue swelling, and fever as well as combat gut and bladder issues. Today, the properly processed horse chestnut seed extract holds promise for treating leg vein problems (chronic venous insufficiency), hemorrhoids, and swelling (edema) .
Other, less widely investigated claimed benefits of horse chestnuts are to increase male fertility, relieve eczema, reduce menstrual pain, and heal skin sores .
Escin shouldn’t be confused with esculetin – the poisonous ingredient in non-processed horse chestnuts .
Horse chestnut seed extract also contains antioxidant, anti-inflammatory, and potentially cancer-fighting flavonoids and phenolic acids such as :
Escin in horse chestnut seeds acts by:
- Reducing swelling by strengthening and narrowing blood vessels (via calcium channels) 
- Strengthening blood vessels (increasing prostaglandin F2)
- Reducing blood clotting and blood pressure (by reducing platelet aggregation) 
- Reducing inflammation (by blocking nitric oxide)
- Reducing allergies (by suppressing white blood cells) 
- Fighting cancer by increasing cancer cell death (apoptosis) and autophagy while decreasing their growth and spreading [9, 10]
Leg vein problems can result in chronic venous insufficiency (CVI). Valves in veins help carry blood from the legs back to the heart. When the valves become weakened or damaged, they may cause swelling, pain, fatigue, tension, and itching in the legs.
Numerous human studies confirm the benefits of horse chestnuts for treating chronic vein problems. Horse chestnut seeds reduced the number of fluids in lower legs as well as ankle and calf swelling in people with chronic leg problems in a systematic review of 17 studies .
Compared to placebos, horse chestnut (taken for 2-12 weeks in oral doses of 100-150 mg daily) reduced leg swelling, pain, fatigue, and itching based on 21 clinical trials involving ~12,000 CVI patients .
Taken together, the existing evidence suggests that horse chestnut helps with chronic vein problems. Note, however, that this herbal supplement is not approved by the FDA for this condition. You may discuss with your doctor if it could be helpful in your case. Never take horse chestnut supplements in place of what your doctor recommends or prescribes.
Edema is caused by the buildup of fluids under the skin, leading to swelling. It can affect the lower legs and feet, and symptoms include stiff joints, aching limbs, skin color changes, and weight gain .
In two clinical trials, 125 patients who received escin injections (5-10 mg twice a day) after surgery noticed reduced temperature and swelling 3-4 days after surgery .
Escin also increased the contraction of veins, helping to push blood back to the heart and decrease swelling (via reducing calcium sensitivity) in rat muscle cells .
Although promising, the existing evidence is insufficient to conclude for certain that horse chestnut reduces swelling. Further clinical research is needed.
Hemorrhoids are also caused by swollen veins in the anus.
In a study of 80 patients with hemorrhoids, escin (40 mg) improved bleeding and swelling in over 80% of patients during two months .
A single clinical trial cannot be considered sufficient evidence that horse chestnut’s escin improves hemorrhoids. This preliminary result should be replicated in additional clinical trials.
In a study of 219 Chinese male patients with infertility (due to prostate vein swelling) 60 mg of escin for 2 months improved sperm quality, motility, and amount (by at least 30%) .
As was the case for hemorrhoids, a single clinical trial is insufficient to claim that escin improves fertility issues due to prostate vein swelling. More clinical studies are needed.
Clinical testing of 3% horse chestnut gel on 40 female volunteers (3 times a day, 9 weeks) diminished wrinkles around the eyes compared to the controls .
Again, only one clinical trial supports this potential benefit of horse chestnut. More clinical trials on larger populations are needed to confirm this preliminary finding.
In a clinical trial, escin from horse chestnut (5 mg twice daily, intravenous, 2 weeks) reduced inflammation in 24 women with vein problems. It acted by blocking the release of inflammatory compounds and reducing the activation of immune cells that increase inflammation .
In dogs, the leaves of horse chestnuts have been used to reduce swelling in gum disease .
A small clinical trial, a study in dogs, and a cell-based study are insufficient to conclude that horse chestnut helps with inflammation. Further clinical research is warranted.
No clinical evidence supports the use of horse chestnut for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.
Escin may strengthen small blood vessels (capillaries) that otherwise become swollen when weakened.
In a tissue study on human leg veins, escin increased the tone of veins (contracting them due to increased PGF-2) .
Escin also blocked enzymes that break down blood vessel walls, prevented leakage, and maintained the structure of capillaries. Daily escin (1 mg/kg) reduced breakdown of rat tissue over 3 weeks .
In mice, escin increased gut flow and decreased inflammation. Gut flow in mice with paralyzed gut muscles improved with escin supplementation .
Escin from Japanese horse chestnut reduced blood sugar levels in mice given large amounts of sugar (glucose tolerance test). This could be important for treating both diabetes and obesity, although research in humans is needed [21, 22].
Diabetic complications can damage the kidneys. In diabetic rats with kidney damage, horse chestnut seed extract reduced inflammation and markers of kidney damage (blood urea nitrogen, and creatinine). Horse chestnuts were capable of restoring kidney function .
Horse chestnut seed extract protects cells and reduces inflammation, which is linked to anti-aging effects. These qualities, along with escin’s “gentle, soapy feel,” suggest the potential use of horse chestnuts in cosmetics. However, research in humans is lacking .
Keep in mind that the safety profile of horse chestnut is relatively unknown, given the lack of well-designed clinical studies. The list of side effects below is not a definite one and you should consult your doctor about other potential side effects based on your health condition and possible drug or supplement interactions.
When prepared correctly, horse chestnuts have few side effects. In some cases, the purified extract can still cause severe skin rash, dizziness, upset stomach, and headache. Horse chestnut damaged red blood cells in rabbits given a high dose for a month (about 10 times greater than the usual dose), but no other toxic effects have been recorded .
Although escin is likely effective for leg vein problems, make sure to speak with a healthcare professional about the treatment if you suffer from venous disease.
Other claimed benefits of escin such as menstrual pain relief do not have studies to back them up. Long-term use has not been evaluated and is not recommended.
Due to lack of research, the use of escin in children, pregnant or breastfeeding women is not recommended.
While multiple clinical trials have researched the benefits of horse chestnut for vein problems, other potential health benefits have been investigated in only a few, small trials or only tested in animals and cells. More clinical research is needed to confirm their preliminary results.
Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
Since horse chestnut can reduce blood clotting, it can interact with drugs that have a similar effect (ibuprofen, aspirin, naproxen, warfarin, and others) and increase the risk of bleeding .
Horse chestnut is an herbal supplement that can be purchased as a cream, capsule (dry) or liquid extract.
Today, most horse chestnut extracts are made from the seed as opposed to the leaf or bark since the seed contains the highest concentration of escin .
Because horse chestnut is not approved by the FDA for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor which may be the optimal dose in your case.
With this in mind, horse chestnut dosage depends on the sought-after health benefit.
The maximum oral dose recommended for use in humans per day is 150 mg .
Standardized horse chestnut extracts contain around 20% of escin .
The studied dose for escin injections is 5-10 mg twice daily for up to 2 weeks .
Creams with horse chestnut contain 2% escin and are applied 3-4 times a day up to 2 months .
The opinions expressed in this section are solely those of horse chestnut users who, may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.
Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
Some users said horse chestnut seed extract helped them with irregular fat distribution (lipedema) and reduced swelling. However, one user reported frequent nausea and vomiting after taking the supplement.
Most users took horse chestnut with food to avoid stomach upset.
Many users mentioned that horse chestnuts were effective in reducing varicose veins and leg swelling. Some reported leg cramping as a major side effect, as well as chest pain, and headaches.
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