\u00a9 2020 wikiHow, Inc. All rights reserved. Take antihistamines. scalp itchy after hair dye. If you have any pain or tenderness, a rash, or sores on your scalp after using hair dye, it’s likely that you’ve had an allergic reaction to an ingredient in the dye. Several natural products can help treat various conditions that cause itchy scalp. This image may not be used by other entities without the express written consent of wikiHow, Inc.