Croup (laryngotracheobronchitis) is acute inflammation of the upper airway, predominantly subglottic, most often caused by parainfluenza virus types 1-3. Hallmarks: barking ("seal-like") cough, inspiratory stridor, hoarse voice, low-grade fever. Age 6 months-6 years, peak 2 years. Indian epidemiology: peaks late monsoon and winter.

• Dexamethasone 0.6 mg/kg (max 16 mg) PO or IM — single dose, even in mild croup. Reduces re-attendance and admission. Available as Decadron, Wymesone, Dexona; cost ₹5-15 per dose.
• Nebulised adrenaline — L-epinephrine 1:1000 (5 mL) OR racemic epinephrine 0.05 mL/kg of 2.25% (max 0.5 mL). Effect peaks ~30 min, lasts 2-3 h. Observe ≥ 3 h after nebulisation to detect rebound.
• Oxygen only if hypoxic (SpO₂ < 92%) — masks can agitate child and worsen obstruction.
• Minimise handling — let the child sit on the parent's lap.
• Antibiotics not indicated (viral) unless bacterial tracheitis suspected.

• Epiglottitis — toxic-looking, drooling, tripod posture, no barking cough. Rare since Hib vaccine but still seen in unvaccinated rural children. Emergency intubation in OT.
• Bacterial tracheitis — high fever, toxic, doesn't respond to adrenaline neb. Needs IV antibiotics + airway management.
• Foreign body aspiration — sudden onset, history of choking, unilateral wheeze. Rigid bronchoscopy.
• Retropharyngeal abscess — fever, neck stiffness, drooling, neck extended. Needs CT/USG, surgical drainage.
• Anaphylaxis — rapidly progressive, urticaria, history of trigger. IM adrenaline.