Some indicators that you should not have a perm done at a particular time include: you normally consume well-water (which tends to have more iron) your scalp is already irritated or injured your scalp is sunburned your scalp has scratches or brush marks (you should not brush for 3 days before getting a perm) you have had prior reactions to straighteners you have a negative reaction to a strand test you have recently had other hair procedures or treatments done that could adversely react or impact a perm