Delivery technique (pMDI 100 mcg/actuation + valved holding chamber (spacer) — **1 puff at a time** with **5 tidal breaths** per puff; face mask if age <4 years or poor lip seal; shake inhaler before use (BTS/SIGN 158, GINA 2025, Australian Asthma Handbook))
Max 1 mg/dose · Duration: PRN · 1 puff/kg (100 mcg/puff) — max 10 puffs (1 mg)/dose; repeat q20–30 min first hour, then q1–4 h PRN
• Maximum per dose: **10 puffs (1000 mcg = 1 mg)** — applies to all MDI+spacer strategies regardless of weight (BTS/SIGN 158, GINA 2025, RCH).
• Maximum in first hour: up to **3 doses** at q20–30 min intervals → theoretical max **30 puffs (3 mg)** if q20 min × 10 puffs; practical moderate exacerbation typically needs **2–3 doses** totalling 4–10 puffs each (BTS/SIGN 158, WHO Pocket Book).
• Hourly ceiling (safety): avoid cumulative salbutamol toxicity — if ≥3 MDI doses in first hour with persistent moderate–severe symptoms, add **ipratropium**, give **systemic steroid**, and consider **nebulized** or **admission** rather than further escalating puff count alone (BTS/SIGN 158, GINA 2025).
• Mild attack shortcut: **2–4 puffs** (0.2–0.4 mg) once, reassess 20 min — additional puffs up to 10 total if incomplete relief (BTS/SIGN 158).
• Do **not** use oral or IV salbutamol for routine acute bronchospasm — inhaled route preferred; monitor for toxicity (tachycardia, tremor, hypokalaemia, metabolic acidosis) with repeated inhaled doses (GINA 2025, RCH, BTS/SIGN 158).
• Severe exacerbation with inadequate response to 2–3 MDI+spacer doses: switch to back-to-back **nebulized** salbutamol q20–30 min ± ipratropium — see Acute Asthma Exacerbation card for full pathway (BTS/SIGN 158).
• Home/community: families should have pMDI+spacer action plan; reserve nebulizer for children with established home nebulizer use per asthma action plan — ED/hospital nebulization does not require home nebulizer prescription (GINA 2025, AAP).
• Continuous nebulization: **not routine** — intermittent q20–30 min equivalent hourly dose preferred per BTS/SIGN 158; continuous infusion reserved for PICU/severe life-threatening per institutional protocol — see Nebulized variant (GINA 2025, BTS/SIGN 158).
Enter weight on Kids to calculate doses
Clinical notes
• pMDI + spacer **preferred** over nebulizer when feasible — equivalent bronchodilation, fewer side effects, faster delivery, lower aerosol infection risk; teach caregivers 1 puff + 5 breaths technique with mask for young children (BTS/SIGN 158, GINA 2025, NICE NG51).
• Repeat interval: **q20–30 min** in first hour while symptoms persist — typical moderate case needs 2–3 doses; when improving, space to q1–4 h; document puff count per dose and cumulative first-hour total to avoid salbutamol toxicity (BTS/SIGN 158, WHO Pocket Book).
• Adverse effects: **tachycardia**, **tremor**, **hypokalaemia**, nausea, headache; rare paradoxical bronchospasm — risk increases with repeated high cumulative doses; metabolic acidosis with excessive β2 agonist use (GINA 2025, RCH, BTS/SIGN 158).
• Monitoring: **HR**, **RR**, **SpO2**, work of breathing, and consciousness before/after each dose; check **serum K+** if prolonged/repeated dosing, IV salbutamol co-administration, or on diuretics/corticosteroids; ECG if severe tachycardia or arrhythmia concern (BTS/SIGN 158, RCH).
