What is it called when a person is highly sensitive to an allergen?

When a person is highly sensitive to an allergen, it is referred to as having a "severe allergy" or "anaphylaxis" in extreme cases. This heightened sensitivity can trigger strong immune responses upon exposure to the allergen, leading to symptoms such as hives, swelling, difficulty breathing, or even life-threatening reactions. Individuals with severe Allergies often need to take precautions to avoid exposure and may carry emergency medications, like epinephrine auto-injectors.