Horse chestnut has been shown to have a tonifying effect on the venous system and is used both internally and externally for varicose veins, hemorrhoids, and phlebitis. It increases blood circulation, reducing fragility and leakage from tiny vessels, and can be used long term for leg cramps that occur at night. Recently, extracts from horse chestnut, called aescin, have been added to creams and other preparations used externally for sports injuries such as sprains and strains, bruises, and venous problems.