The invention is directed to a mouth piece for cooling of oral tissue of a patient during chemotherapy treatment. The mouth piece includes a cooling medium contained within the top element and the bottom element and able to retain a cooling environment within the mouth sufficient to reduce capillary blood flow to the patient's mouth. In one embodiment, an external chamber extends from the front of the mouth piece to house a cooling medium. The external chamber can be configured so that it is removably attached to the mouth piece. A support device can be utilized to support the external chamber during use.