Chart — Med-Surg
Hypersensitivity Reaction Types Chart
Hypersensitivity is the immune system overreacting or misfiring. The four classic types are sorted by mechanism and timing — and once you anchor one signature example to each, the rest of the exam questions fall into place.
Educational use only. This chart is for study and pattern recognition; diagnosis and management of immune reactions are provider-directed. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Types I–IV Side by Side
| Type | Mechanism | Timing | Classic Examples |
|---|---|---|---|
| Type I — Anaphylactic (immediate) | IgE-mediated; mast cell and basophil degranulation releasing histamine | Seconds to minutes | Anaphylaxis, allergic asthma, allergic rhinitis, hives, food/drug/insect allergy |
| Type II — Cytotoxic | IgG/IgM antibodies bind antigens on cell surfaces → cell destruction (complement) | Minutes to hours | ABO-incompatible transfusion reaction, hemolytic disease of the newborn, autoimmune hemolytic anemia, Goodpasture |
| Type III — Immune complex | Antigen-antibody complexes deposit in tissues → inflammation | Hours to days | SLE (lupus), rheumatoid arthritis, serum sickness, post-streptococcal glomerulonephritis |
| Type IV — Delayed (cell-mediated) | T-cell mediated; no antibodies | Delayed — 48–72 hours | PPD/TB skin test reaction, contact dermatitis (poison ivy, latex, nickel), transplant rejection |
The ACID Mnemonic
Anaphylactic (I) · Cytotoxic (II) · Immune complex (III) · Delayed (IV). The timing climbs with the number: Type I is immediate, Type IV is the slow 48–72-hour reaction — which is exactly why a TB skin test is read two to three days later.
NCLEX Pearls
- ✦Type I is IgE-mediated and immediate — anaphylaxis is the must-recognize emergency (epinephrine first).
- ✦ABO-incompatible transfusion reaction is Type II (cytotoxic) — stop the transfusion immediately.
- ✦Lupus and serum sickness are Type III (immune complexes deposit in tissue).
- ✦PPD reaction, poison ivy, and contact/latex dermatitis are Type IV — delayed and T-cell mediated, no antibodies.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with Academy of Medical-Surgical Nurses (AMSN) · Current medical-surgical nursing standards. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →