Why do we itch?

Itching is actually a defense mechanism in our body that warns us that our skin has come in contact with some irritant - a bug, a hair or clothing fibers to name a few. As soon as something irritates the skin, nerves present in the upper layers of the dermis respond to the stimulus. Special white cells, called mast cells, are clustered around the endings of the nerve receptors and produce a chemical, histamine, which interacts with the receptors. When histamine is released, we experience an itching sensation. People with allergies overproduce histamine when exposed to the allergic substance.

The nerve receptors also send a signal to the cerebral cortex of the brain. Brain scans have shown that when an itch is perceived, the part of the brain involved in planning a motor task is activated. The brain then prompts us to scratch the area and remove the irritant from the skin.

Resources:

Further information about why we itch is available at Science Shack and HowStuffWorks.

Find some possible causes for itching.

Learn about how to relieve some types of itching.