Anaphylaxis
Serum tryptase levels increase on degranulation of mast cells, so serum tryptase levels may aid in diagnose of anaphylaxis when the history of the event is not clear or available.
Treatment at a glance
- Adrenaline IM 0.5 mg (adult) into the thigh, repeat after 5 minutes
Anaphylaxis
- Life-threatening allergic reaction.
Read this in Blood Transfusion Contraindications & Acute Reactions
What our notes say
- Serum tryptase levels increase on degranulation of mast cells, so serum tryptase levels may aid in diagnose of anaphylaxis when the history of the event is not clear or available. (Immunopathology complete mcqs — Past Paper Questions & Answers)
- A man with a penicillin allergy that caused anaphylaxis has cellulitis. (Pharmacology Question Bank: 15 Clinical MCQs)
- g) Heart conditions - cute episode of congestive heart failure h) serious allergic reaction (anaphylaxis), (Examination of Respiratory system — Past Paper Questions & Answers)
- • An injury, infection, burns or a severe allergic reaction (anaphylaxis) that causes the throat to become swollen and narrowed (Examination of Respiratory system — Past Paper Questions & Answers)
- Tryptase levels serve as a marker for mast cell burden and risk for anaphylaxis. (Immunopathology complete mcqs — Past Paper Questions & Answers)
- Increased vascular permeability: acute inflammation, anaphylaxis/allergic reactions. (Eoy paper 2 gen systemic Patho 2025 — Past Paper Questions & Answers)
Study material on Anaphylaxis
- Immunopathology Cat: Hypersensitivity & Anaphylaxis MCQs
- Immunopathology complete mcqs
- Immunopathology
- MBPL3822 Chemotherapy CAT 1 MCQs
- Blood Transfusion: ABO, Rh Blood Groups, Compatibility & HDN
- Cestodes (Tapeworms)
- Master Blood Transfusion: A Medical Quiz on Reactions & Tests
- MBPL3822 Chemotherapy CAT 1 MCQs
Practice questions on Anaphylaxis
A 68-year-old man presents from a nursing home with fever, increased urinary frequency and urgency, and mental status changes. He has a penicillin allergy of anaphylaxis. Which of the following β-lactams is the most appropriate choice for gram-negative coverage of this patient's urinary tract infection?
- Aztreonam
- Ceftaroline
- Cefepime
- Ertapenem
- Primarily an incidental laboratory finding
Answer: A. Aztreonam is a monobactam with no cross-reactivity with penicillins and can be safely given to penicillin-allergic patients, even those with anaphylaxis. Although cross-reactivity between cephalosporins/carbapenems and penicillins is low (<1-10%), the risk rarely outweighs the benefit in cases of documented anaphylaxis. Aztreonam provides good gram-negative coverage for UTI. ---
Your 23-year-old female patient is pregnant and has gonorrhea. The past medical history includes anaphylaxis following exposure to amoxicillin. Worried about compliance, you would like to treat this patient with a single dose, so you chose
- Ciprofloxacin
- Spectinomycin
- Cefixime
- Ceftriaxone
- Tetracycline
Answer: A. Spectinomycin is an aminocyclitol antibiotic that can be given as a single intramuscular dose for gonorrhea. It has no cross-reactivity with penicillins (safe in penicillin allergy) and is safe in pregnancy. Ceftriaxone and cefixime have potential cross-reactivity with penicillins. Ciprofloxacin and tetracycline are contraindicated in pregnancy. ---
Which is the treatment of choice in a child with signs of anaphylaxis after being stung by three bees?
- Diphenhydramine
- Ephedrine
- Epinephrine
- Dexamethasone
- Isoproterenol
Answer: C. Epinephrine is the first-line treatment for anaphylaxis. It acts on α1 receptors (vasoconstriction to reverse hypotension), β1 receptors (increased cardiac output), and β2 receptors (bronchodilation). It also stabilizes mast cells, preventing further mediator release. Route: IM into anterolateral thigh. --- ---
A patient with known IgA deficiency develops anaphylaxis during transfusion. What component should they receive in future?
- Irradiated blood
- Washed red cells
- IgA-deficient plasma
- Leucocyte-reduced blood
- Platelets ✅ Answer: A
Answer: A. While washed red cells or IgA-deficient plasma are appropriate for IgA deficiency with anaphylaxis, the provided answer sheet indicates irradiated blood.
Which is the treatment of choice in a child with signs of anaphylaxis after being stung by three bees?
- Diphenhydramine
- Ephedrine
- Epinephrine
- Dexamethasone
- Isoproterenol
Answer: C. Epinephrine is the first-line treatment for anaphylaxis. It acts on α1 receptors (vasoconstriction to reverse hypotension), β1 receptors (increased cardiac output), and β2 receptors (bronchodilation). It also stabilizes mast cells, preventing further mediator release. Route: IM into anterolateral thigh. --- ---
Which is the treatment of choice in a child with signs of anaphylaxis after being stung by bees?
- Diphenhydramine intramuscularly
- Albuterol nebulizer
- Epinephrine intramuscularly
- Hydrocortisone intravenously
Answer: C. Epinephrine is the first-line treatment for anaphylaxis due to its ability to cause vasoconstriction, bronchodilation, and decreased mediator release.