[W]hen any one has an aching head, or arm, or stomach, they say that a Manitou has entered this part of the body, and will not cease its torments until it has been drawn or driven out. (Claude Allouez, 1667) Medicine man curing a patient. Original lithograph based on a watercolor by Seth Eastman, 1853. (Robert E. Warren collection)

When a person experienced health problems associated with a serious illness or injury, they requested the assistance of a shaman. A shaman was a man or woman with access to supernatural healing powers. When summoned, the shaman would often shake a gourd rattle and appeal to his or her own personal manitou to help diagnose the problem and to provide knowledge of special medicines and healing rituals. In many cases, the shaman applied medicinal plants to the affected part of the body and then sucked on it to extract the offending manitou. The patient's family was expected to pay the shaman with a kettle full of gifts.

Rattlesnakes abound among them and every year someone is bitten. This troubles them but little since they have an excellent root which softens the swelling as soon as it is applied to the wound, so that by next day the patient is cured. (Pierre Delliette, 1702)

Illinois shamans used medicinal plants to help cure sick or injured patients, but few of the plant species have been identified. For example, Pierre Delliette, a French fur trader who lived among the Illinois, described a plant used to cure rattlesnake bites. It was a prairie plant that stood about two feet tall and had narrow leaves, large seed-bearing buds, and an onion-shaped root. This plant may have been rattlesnake master (Eryngium yuccifolium), a prairie plant used by the Fox (Mesquakie) Indians to cure rattlesnake bites, but the identification is not certain. Other medicinal plants that may have been used by the Illinois include boiled root of basswood (Tilia americana) for burns, boiled root or bark of white oak (Quercus alba) for wounds, powdered root of wild ginger (Asarum canadense) for childbirth pain, and sumac (Rhus sp.) for diarrhea.