What does it mean to have an allergy?

An allergy refers to an abnormal sensitivity to a substance, typically involving an immune response to a foreign material, which can be food, pollen, dust, or certain medications. When a person is allergic to a substance, their immune system mistakenly identifies it as a harmful agent and reacts to it, often causing symptoms that can range from mild to severe, such as itching, swelling, rashes, or even anaphylaxis in extreme cases.

In contrast, extreme sensitivity to light relates to photophobia and has no direct correlation with the immune response related to allergies. Resistance to infections refers to the body's ability to fight off pathogens, which is a distinct concept from allergies, as it involves immunity rather than hypersensitivity. General intolerance to medications, while possibly involving adverse reactions, is not synonymous with allergies, as it may not always involve the immune system’s response. Therefore, understanding that an allergy is essentially an abnormal sensitivity helps clarify the nature of allergic reactions and their implications for patient care and safety in a pharmacy setting.