Which chemical is known for causing skin to itch?

Histamine is a chemical that plays a significant role in the body’s immune response and is primarily associated with allergic reactions. When the body is exposed to allergens, mast cells release histamine, which leads to various physiological effects. One of its key functions is to increase the permeability of blood vessels, allowing white blood cells and other proteins to access affected tissues. This process can lead to symptoms such as redness, swelling, and itching.

The itching sensation occurs because histamine stimulates nerve endings in the skin, prompting the sensation that is often perceived as a need to scratch. This is a common response to allergens and is seen in conditions such as hay fever, hives, and other allergic skin reactions.

Other chemicals listed, such as serotonin and cortisol, serve different functions in the body. Serotonin primarily affects mood and well-being, while cortisol is involved in the body's stress response and has anti-inflammatory properties. Prostaglandins are involved in the inflammatory process and can contribute to pain and fever but are not directly responsible for the sensation of itching in the same way histamine is.