Histamines are natural chemicals produced by the body, primarily involved in the immune response. They are released during allergic reactions and play a key role in signaling the body to respond to allergens, such as pollen or pet dander. When histamines are released, they can cause symptoms like itching, sneezing, and swelling. In addition to their role in allergies, histamines also help regulate various bodily functions, including stomach acid production and neurotransmission in the brain. There are different types of histamine receptors, which mediate their effects in various tissues, influencing processes like inflammation and gastric secretion.