Asthma
Exam Tips
- In OSCEs, emphasise variability: variable symptoms + variable expiratory airflow limitation is central to diagnosis.
- Uncontrolled asthma includes exacerbations needing oral steroids and frequent reliever use (e. g, >=3 days/week) or night waking.
- Always mention inhaler technique and adherence before stepping up treatment; this is a common exam trap.
- State explicitly that LABA monotherapy is unsafe in asthma; LABA should be paired with ICS.
- Red flags for asthma death risk: previous ICU/intubation, recent admission, SABA overuse, poor ICS adherence, psychosocial problems, food allergy/anaphylaxis.
- Differentiate difficult-to-treat asthma (modifiable factors/comorbidity/adherence) from true severe refractory asthma.
Definition
Asthma is a chronic inflammatory airway disorder with variable expiratory airflow limitation and bronchial hyper-responsiveness, causing recurrent wheeze, breathlessness, chest tightness, and cough. Symptoms fluctuate over time (often worse at night/early morning) and may be spontaneous or trigger-related, with acute exacerbations ranging from mild to life-threatening.
Pathophysiology
Core mechanisms are type 2 and non-type 2 airway inflammation, episodic bronchoconstriction, mucosal oedema, and mucus hypersecretion. In allergic disease, allergen exposure drives Th2 cytokines (IL-4, IL-5, IL-13), IgE production, eosinophilic inflammation, and mast-cell mediator release; viral infection, pollutants, and irritants can amplify this. Repeated inflammation leads to airway remodelling (subepithelial fibrosis, smooth-muscle hypertrophy, goblet-cell hyperplasia), explaining persistent symptoms and possible fixed airflow limitation in some patients. See Figure: schematic of airway inflammation and remodelling in standard respiratory pathology texts.
Risk Factors
- Personal or family atopy (asthma, eczema, allergic rhinitis, nasal polyps)
- Allergen sensitization (house dust mite, animal dander, pollens, mould)
- Comorbid allergic rhinitis/chronic rhinosinusitis (especially with nasal polyps)
- Food allergy (especially in children)
- Smoking exposure (active/passive; including vaping aerosols)
- Obesity and deconditioning
- Preterm birth or low birth weight
- Occupational exposure (e. g, flour dust, isocyanates, cleaning chemicals, laboratory animals, wood dust, welding fumes)
- Female sex for persistent adult asthma; male predominance in childhood
- Drugs that can worsen asthma (non-selective beta-blockers, aspirin/NSAIDs in sensitive patients)
Clinical Features
Symptoms
- Episodic wheeze
- Shortness of breath
- Chest tightness
- Cough (often nocturnal or early morning; may be cough-variant asthma)
- Variable symptoms triggered by exercise, viral URTI, allergens, cold air, laughter/crying, smoke, weather changes
- Nocturnal waking and reliever overuse in poor control
Signs
- Expiratory polyphonic wheeze
- Prolonged expiratory phase
- Tachypnoea and tachycardia during exacerbation
- Use of accessory respiratory muscles in acute attacks
- Reduced peak expiratory flow versus personal best/predicted
- Severe/life-threatening features: inability to complete sentences, exhaustion, silent chest, cyanosis, altered consciousness
Investigations
Management
Lifestyle Modifications
- Provide a personalised written asthma action plan with clear escalation and emergency advice
- Check and correct inhaler technique at every review; reinforce adherence
- Smoking cessation and avoidance of passive smoke/vape exposure
- Trigger reduction: allergen/occupational exposure control; consider workplace assessment for suspected occupational asthma
- Weight optimisation, physical activity, and management of rhinitis/sinus disease/reflux/anxiety where relevant
- Annual influenza vaccination; pneumococcal vaccination as clinically indicated
Pharmacological Treatment
Reliever (SABA) for breakthrough symptoms
- Salbutamol inhaler 100 micrograms/puff: 1-2 puffs when required (typical max 200 micrograms up to 4 times daily in routine use)
- Terbutaline dry powder inhaler 500 micrograms per inhalation when required
Frequent SABA need indicates poor control and increased risk; review urgently if reliever needed >=3 days/week. In acute attacks, repeated high-dose SABA via spacer/nebuliser is used per emergency protocol.
Inhaled corticosteroid (ICS) maintenance
- Beclometasone dipropionate (standard particle) 100-200 micrograms twice daily (low-dose range)
- Budesonide 200-400 micrograms twice daily
- Fluticasone propionate 100-250 micrograms twice daily
ICS is foundational controller therapy. Advise mouth rinsing after use to reduce candidiasis/dysphonia. Monitor growth in children and adrenal effects at prolonged high dose.
Combination ICS/LABA (including MART where appropriate)
- Budesonide/formoterol DPI 200/6: typically 1 inhalation twice daily maintenance, plus 1 inhalation as needed for symptoms (MART); usual maximum 12 inhalations/day total
- Beclometasone/formoterol 100/6: maintenance dosing with additional reliever use in MART regimens according to product limits
Do not use LABA without ICS in asthma. MART reduces severe exacerbations in suitable patients; ensure patient understands maximum daily inhalations and when to seek urgent care.
Add-on controller options
- Montelukast 10 mg at night (adults)
- Tiotropium Respimat 5 micrograms once daily
- Modified-release theophylline 200-400 mg twice daily (titrate to plasma levels)
Montelukast: warn about possible neuropsychiatric adverse effects (sleep disturbance, mood/behaviour change). Theophylline has a narrow therapeutic index and major interactions (e. g, macrolides, quinolones); monitor levels and toxicity.
Acute exacerbation treatment
- Prednisolone 40-50 mg orally once daily for at least 5 days (or until recovery)
- Nebulised salbutamol 2.5-5 mg repeated as needed; add nebulised ipratropium bromide 500 micrograms in severe attacks
- Intravenous magnesium sulfate 1.2-2 g over 20 minutes for severe/life-threatening exacerbation not responding adequately
Assess severity early and escalate promptly if life-threatening features. Avoid sedation. Give controlled oxygen to target saturation 94-98% unless risk of hypercapnic failure dictates otherwise.
Severe eosinophilic/allergic asthma biologics (specialist care)
- Mepolizumab 100 mg subcutaneously every 4 weeks
- Benralizumab 30 mg subcutaneously every 4 weeks for first 3 doses, then every 8 weeks
- Dupilumab 200 mg or 300 mg subcutaneously every 2 weeks (indication-dependent)
- Tezepelumab 210 mg subcutaneously every 4 weeks
- Omalizumab subcutaneous dose based on IgE and body weight
Reserved for uncontrolled severe asthma after optimisation of standard therapy. Monitor for hypersensitivity/anaphylaxis and reassess response regularly.
Complications
- Acute severe or life-threatening exacerbation with respiratory failure
- Pneumothorax or pneumomediastinum during severe attacks
- Secondary pneumonia
- Persistent airflow limitation from airway remodelling (fixed obstruction phenotype)
- Reduced quality of life, school/work absence, and exercise limitation
- Anxiety/depression with poorer adherence and control
- Asthma-related mortality (higher risk with prior near-fatal attack, recent hospitalisation, poor ICS adherence, or SABA overuse)
- Occupational consequences including job loss and progressive decline if exposure continues
Prognosis
Course is variable: some children remit, but many have persistent or relapsing disease into adulthood, especially with severe childhood symptoms, atopy, smoke exposure, or airway hyper-responsiveness. Adult-onset asthma is less likely to remit, and severe disease may need long-term high-intensity treatment. Prognosis improves with early diagnosis, consistent ICS-based therapy, trigger control (including occupational exposure cessation), and robust self-management planning.
Sources & References
🏥BMJ Best Practice(1)
💊BNF Drug References(50)
- Acebutolol[contraindications]
- Adenosine[contraindications]
- Alfentanil[cautions]
- Anakinra[cautions]
- Aspirin[cautions]
- Atenolol[contraindications]
- Bimatoprost[cautions]
- Bisoprolol fumarate[contraindications]
- Buprenorphine[cautions]
- Carvedilol[contraindications]
- Celiprolol hydrochloride[contraindications]
- Codeine phosphate[cautions]
- Co-tenidone[contraindications]
- Dexketoprofen[cautions]
- Diclofenac sodium[contraindications]
- Dihydrocodeine tartrate[cautions]
- Dinoprostone[cautions]
- Esmolol hydrochloride[contraindications]
- Ferric carboxymaltose[cautions]
- Ferric derisomaltose[cautions]
- Labetalol hydrochloride[contraindications]
- Landiolol hydrochloride[contraindications]
- Latanoprost[cautions]
- Lauromacrogol 400[contraindications]
- Loxapine[contraindications]
- Meptazinol[cautions]
- Methadone hydrochloride[cautions]
- Metoclopramide hydrochloride[cautions]
- Metoprolol tartrate[contraindications]
- Nadolol[contraindications]
- Nebivolol[contraindications]
- Opium[cautions]
- Oxycodone hydrochloride[cautions]
- Pentazocine[cautions]
- Pilocarpine[cautions]
- Pindolol[contraindications]
- Propranolol hydrochloride[contraindications]
- Pyridostigmine bromide[cautions]
- Remifentanil[cautions]
- Rivastigmine[cautions]
- Sodium tetradecyl sulfate[contraindications]
- Sotalol hydrochloride[contraindications]
- Sufentanil[cautions]
- Sulfadiazine[cautions]
- Tapentadol[cautions]
- Tetracosactide[contraindications]
- Ticagrelor[cautions]
- Timolol maleate[contraindications]
- Travoprost[cautions]
- Vasopressin[cautions]
✅NICE Guidelines(1)
- Asthma[overview]
📖Textbook References(1)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 581)[context]