Horse chestnut comes from the seeds of *Aesculus hippocastanum*. The key active, aescin, works by reinforcing vein walls and cutting down on fluid leakage into surrounding tissue.
People take it as a standardized capsule or tablet, usually with a meal to avoid an upset stomach. Daily doses are based on aescin content, which varies between brands, so follow the label closely.
Never eat raw horse chestnut seeds. They are toxic. This botanical can interact with blood thinners like warfarin, aspirin, and clopidogrel. Anyone with liver or kidney conditions should be careful. Skip it if you are pregnant or breastfeeding. Some people notice mild digestive discomfort.