When scratching a dry and itchy body during winter, the itchiness can sometimes worsen. Why does scratching make the itchiness more intense? It is related to serotonin, a neurotransmitter in the brain.

When external irritants come into contact with the skin, an itching sensation is felt as a response. At this time, the skin stimulation caused by scratching is perceived by the body as a mild pain. When the pain is transmitted to the brain, the brain secretes serotonin to improve mood and forget the pain.

Serotonin tends to activate nerve cells (neurons) that transmit the sensation of itch to the brain. As serotonin is secreted, nerve cells become activated, making individuals more sensitive to itching and causing them to scratch more.

According to a study at Washington University in the United States, mice with the serotonin secretion gene removed did not scratch their bodies much even when injected with an itch-inducing substance, but when serotonin was administered, they continued to scratch their bodies.

The exact mechanism by which serotonin activates itch transmission neurons has not yet been fully elucidated. However, it is well established that serotonin secretion is strongly associated with itching.

If you continue to scratch the skin, the outermost barrier of the skin is damaged by physical friction. This makes the skin more vulnerable to external irritants and can increase the sensation of itchiness. Instead of scratching, applying moisturizer frequently can help reduce the feeling of itchiness.

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Thinking it's a little itchy

Scratched it and then

If it continues to itch

I do have it.

Especially the back seems to be more like that.

Itching on dry days

It gets worse.