(HealthDay News) -- The makers of herbal supplements say they can treat or prevent a host of conditions and symptoms, including arthritis, headaches and colds. But you should do your homework when selecting herbal supplements for what ails you, the American Academy of Family Physicians warns.

Although herbal supplements may contain natural ingredients, the AAFP says some of these products also contain potential allergens and chemicals that can make you sick -- and they aren't necessarily listed on the product's label.

Certain people should be especially careful about taking herbal supplements, including those with diabetes, high blood pressure, epilepsy, blood clotting problems, Parkinson's, heart disease, liver or thyroid problems. People with psychiatric conditions or conditions of the immune system also should be particularly cautious, the academy warns.