Histamine is a chemical produced by the body that plays a crucial role in the immune response. It is released during allergic reactions and helps to regulate various physiological functions, such as stomach acid production and neurotransmission. When the body encounters an allergen, histamine is released from certain cells, leading to symptoms like itching, swelling, and redness. In addition to its role in allergies, histamine is also involved in the sleep-wake cycle and acts as a neurotransmitter in the brain. It helps to promote wakefulness and alertness, influencing overall cognitive function and mood. Understanding histamine is important for managing allergies and other related health conditions.