Horse Chestnut is used to treat varicose veins, support circulation, diarrhea, fever and enlarged prostate. Horse Chestnut is widely used in Europe as an anti-inflammatory agent. It may reduce fluid retention increasing the re-absorption of excess fluid back into the circulatory system. Horse Chestnut has also been used for leg ulcers and frostbite, both internally as a capsule and externally as a lotion or gel.