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Medical Emergencies · patient case question

What is the immediate management?

Patient case: Breathlessness after a prescribed antibiotic

Patient: Adult patient with a documented penicillin allergy

Chief complaint: Attended for treatment of a dental infection.

Background: Documented allergy to penicillin. Cephalexin was prescribed.

Current findings: Thirty minutes after the dose he becomes short of breath.

  1. Intramuscular epinephrine into the anterolateral thigh
  2. A salbutamol inhaler alone
  3. An oral antihistamine and observation
  4. An intravenous corticosteroid as the first drug
Show answer and explanation

Correct answer: A. Intramuscular epinephrine into the anterolateral thigh

  • A. CORRECT. Anaphylaxis is treated with EPINEPHRINE without delay — 0.3–0.5 mg of 1:1000 intramuscularly into the anterolateral thigh (vastus lateralis), repeated every 5–15 minutes as required. Adrenaline reverses bronchoconstriction, restores vascular tone and stabilises mast cells. Call emergency services and give oxygen alongside it.
  • B. Salbutamol may help bronchospasm as an adjunct but does not address the vascular collapse.
  • C. An oral antihistamine is far too slow and treats only the cutaneous features.
  • D. Corticosteroids have a role in preventing the biphasic late-phase reaction, but they take hours to act and must never precede adrenaline.

Note: Route matters: IM into the anterolateral thigh gives faster, more reliable absorption than subcutaneous or deltoid injection.

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