Avoid this herb if you are taking blood pressure medicines or have a weak heart. It is also dangerous for diabetics since it will upset blood sugar control. Ma huang combined with digoxin can cause serious heart rhythm disturbances. Feverfew is alleged to prevent migraines, but also serves as an anticlotting agent and may precipitate heavy bleeding if taken before surgery, like aspirin and other anticoagulants. Licorice is now used to treat respiratory infections, ulcers and menopause, but has long been recognized for its ability to deplete body potassium stores, increasing the risk of heart rhythm abnormalities, particularly in patients taking digoxin.
Diuretics also increase potassium loss, so their combination with licorice is very dangerous.
Licorice also interferes with certain blood pressure medications and with blood sugar control in diabetics. Patients taking thyroid replacement may have to adjust their thyroid medication when taking licorice. Black cohash is used to treat menstrual and menopausal symptoms because it contains substances that act like estrogen, the female hormone. It is supposed to alleviate hot flashes, headaches, water retention and premenstrual syndrome. Therefore it falls under the warning not to mix medications with the same effect, in this case, hormone treatment of female conditions.