745 ILCS 10/6-106

(a) Neither a local public entity nor a public employee acting within the scope of his employment is liable for injury resulting from diagnosing or failing to diagnose that a person is afflicted with mental or physical illness or addiction or from failing to prescribe for mental or physical illness or addiction.

(b) Neither a local public entity nor a public employee acting within the scope of his employment is liable for administering with due care the treatment prescribed for mental or physical illness or addiction.

(c) Nothing in this section exonerates a public employee who has undertaken to prescribe for mental or physical illness or addiction from liability for injury proximately caused by his negligence or by his wrongful act in so prescribing or exonerates a local public entity whose employee, while acting in the scope of his employment, so causes such an injury.

(d) Nothing in this section exonerates a public employee from liability for injury proximately caused by his negligent or wrongful act or omission in administering any treatment prescribed for mental or physical illness or addiction or exonerates a local public entity whose employee, while acting in the scope of his employment, so causes such an injury.