Sweet clover seems to be safe for most people when used appropriately. But, it can cause liver damage and bleeding problems when used in large amounts.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the use of sweet clover during pregnancy and breast-feeding. Even though one small study found no harmful effects when used during the last 6 months of pregnancy, stay on the safe side and avoid use until more is known.
Liver disease: There is some concern that sweet clover might make liver disease worse. If you have liver problems, get medical advice before starting sweet clover. Also, be sure to have liver function tests done.
Surgery: Sweet clover might slow blood clotting. Some physicians worry that it might increase bleeding during or after surgery. Stop using sweet clover at least 2 weeks prior to a scheduled surgery.