Allergies || Health Video | MedlinePlus

Allergies are a reaction of the body's immune system to substances that are typically harmless. These substances are known as allergens and can include things like pollen, dust mites, animal dander, certain foods, and insect stings.

When the body encounters an allergen, it produces an antibody called immunoglobulin E (IgE), which triggers the release of histamine and other chemicals. This release causes symptoms such as sneezing, itching, swelling, and in severe cases, anaphylaxis.

There are several types of allergies, including:

Seasonal allergies - also known as hay fever or allergic rhinitis, caused by exposure to airborne allergens such as pollen.

Food allergies - caused by certain foods, such as nuts, eggs, shellfish, and dairy products.

Insect sting allergies - caused by the venom from the sting of an insect, such as a bee or wasp.

Medication allergies - caused by certain medications, such as penicillin or aspirin.

Contact allergies - caused by touching or coming into contact with certain substances, such as latex or poison ivy.

Treatment for allergies typically involves avoiding the allergen when possible, taking medications to relieve symptoms, and in some cases, undergoing immunotherapy to reduce the body's sensitivity to the allergen.