Are Chewing Ice Cubes Harmful For Brain?

Are chewing ice cubes harmful for brain? As i eat earlier ice cubes in a large quantity due to Iron deficiency and after consulting doctor It is fine now. but I have a problem of breath as i can't take it easily from nose or mouth. Then Doctor suggest me a syrup which is neuro stress syrup. By using this syrup and other medicine I am fine. But problem is this as i eat little quantity of ice cubes this problem starts again. Please answer me. Waiting for your kind reply. Thanks