Allergies are hypersensitivities to common substances in the environment or medications that are related to the immune system. Allergies can be diagnosed through blood tests or scratch tests and influenced by both genetics and environment. Common signs of allergy include symptoms affecting the nose, sinuses, eyes, airways, ears, and skin. Hives are swollen, red bumps that appear suddenly on the skin in response to histamine during an allergic reaction and usually itch. Vaccinations introduce the body to viruses and infections to promote antibody production and prevent future sickness or disease outbreaks, saving hundreds of thousands of lives though some have adverse responses. Treatments include avoidance of allergens, diagnosis to prevent accidental exposure,