Horse chestnut (Aesculus hippocastanum) is commonly used in herbal medicine to support vascular health, particularly for chronic venous insufficiency (CVI) and related symptoms such as varicose and spider veins. The primary active compound, aescin, has demonstrated venotonic (vein-tightening) and anti-inflammatory effects in several studies. These actions can help reduce capillary permeability, decrease edema, and improve vein tone, which are relevant to the development and appearance of spider veins.

Multiple randomized controlled trials and systematic reviews have found that standardized horse chestnut seed extract (typically containing 16–20% aescin) can significantly reduce leg pain, swelling, and heaviness in patients with CVI. However, most of these studies focus on larger varicose veins and global symptoms rather than specifically on spider veins (telangiectasias), which are smaller, superficial dilated blood vessels.

While direct evidence for the treatment of spider veins is limited, the improvement in overall venous function and reduction in symptoms associated with vein disorders suggest a plausible benefit. Horse chestnut is widely used in Europe and is recognized by regulatory agencies like the German Commission E for venous system disorders. Nonetheless, more targeted research is needed to confirm efficacy specifically for spider veins.

In summary, horse chestnut’s use for spider veins is based on a moderate level of scientific evidence, primarily extrapolated from studies on venous insufficiency and larger varicose veins.