Histamines are chemicals produced by the body as part of its immune response. They play a crucial role in allergic reactions, helping to protect the body from harmful substances. When the body encounters an allergen, such as pollen or pet dander, histamines are released, leading to 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. Medications like antihistamines are often used to block the effects of histamines, providing relief from allergy symptoms and other conditions.