An allergy is a condition in which your immune system reacts abnormally to typically harmless substances in the environment. The substances that cause these reactions are called allergens. Allergens can be inhaled, ingested, or come into contact with your skin.

Symptoms of an allergic reaction can range from mild to severe. They can include itchiness, sneezing, watery eyes, and a runny nose. In more severe cases, anaphylaxis can occur. This is a potentially life-threatening condition that causes swelling in the throat, difficulty breathing, and a drop in blood pressure.

There are many different causes of allergies. Allergens can come from pollen, dust, mold, animal dander, food, and more. If you have a family history of allergies, you’re more likely to have them.

Allergies can be diagnosed through skin prick tests or blood tests. Treatment options include avoidance of the allergen, medication, and immunotherapy.