Alergic

Alergic is a nonstandard or misspelled form of allergic. In standard medical usage, the correct terms are allergic (adjective) and allergy (noun). An allergic reaction occurs when the immune system overreacts to a normally harmless substance, called an allergen.

Most allergic reactions are IgE-mediated, involving a process in which exposure to an allergen prompts the production of allergen-specific IgE antibodies that sensitize mast cells and basophils. Upon subsequent exposure, these cells release histamine and other mediators, producing symptoms. Not all reactions are purely IgE-mediated; some are non-IgE or mixed in mechanism.

Common triggers include pollen, foods (such as peanuts, milk, eggs, shellfish, and tree nuts), insect venoms, medicines (notably penicillin), latex, and animal dander. Allergies can affect the skin, eyes, nose, airways, or digestive system, and in rare cases can cause anaphylaxis, a life-threatening systemic reaction.

Diagnosis typically relies on medical history and physical examination, supported by tests such as skin prick testing or serum-specific IgE measurements. In some cases, supervised oral food challenges are used to confirm or rule out a food allergy.

Treatment focuses on avoidance of known triggers and management of symptoms. Pharmacologic options include antihistamines, intranasal or inhaled corticosteroids, and, for severe reactions, epinephrine. Allergen immunotherapy (subcutaneous or sublingual) can reduce sensitivity for some allergies over time and may alter the long-term course of the condition.

Management and prognosis vary by individual. Some childhood food allergies resolve with age, while others persist into adulthood. The global prevalence of allergies varies and has been reported to be increasing in many regions, influenced by genetic and environmental factors.