Makindo Medical Notes

Allergic disease is a major cause of respiratory symptoms in both primary and secondary care. 👃 Nasal allergy, 🌬️ asthma, and 🫁 hypersensitivity pneumonitis may all mimic or overlap with infection and other lung disease.

📖 About

• Allergies are inappropriate immune responses to otherwise harmless antigens (allergens).
• Respiratory presentations are very common: allergic rhinitis, asthma, occupational lung disease.
• Immunology: often IgE-mediated (Type I hypersensitivity), triggering mast cell degranulation → histamine, leukotrienes, prostaglandins.

😮‍💨 Clinical Presentations

• 🤧 Allergic Rhinitis (“hay fever”): Sneezing, rhinorrhoea, nasal congestion, itchy eyes, seasonal or perennial.
• 🌬️ Asthma (allergic phenotype): Wheeze, cough (esp. at night/early morning), episodic breathlessness, often with atopy (eczema, allergic rhinitis).
• 🏭 Occupational asthma: Symptoms worse at work, improve away from exposure (e.g. flour, isocyanates).
• 🫁 Hypersensitivity pneumonitis: Dyspnoea, dry cough, fever after antigen exposure (e.g. bird fancier’s lung, farmer’s lung).
• ⚡ Anaphylaxis: Rapid airway swelling, wheeze, stridor, hypotension, urticaria — life-threatening emergency.

🧾 Differentials (Respiratory allergy vs other causes)

• Viral URTI 🤒 — usually acute, self-limiting, not recurrent with exposures.
• Chronic rhinosinusitis — often with polyps, not strictly allergic.
• Non-allergic asthma phenotypes (e.g. eosinophilic, late-onset).
• COPD in smokers — persistent and progressive, less reversible than asthma.

🔬 Investigations

• 🧪 Blood: FBC (eosinophilia), total IgE, allergen-specific IgE (RAST).
• 🌡️ Skin prick testing: Wheal-and-flare response to allergens.
• 📉 Spirometry/Peak flow: Variable obstruction, diurnal variation, reversibility in asthma.
• 📸 Imaging: HRCT if hypersensitivity pneumonitis suspected.
• 🧑‍⚕️ Occupational diary: Peak flow monitoring at and away from work.

💊 Management Principles

• 🚫 Avoidance: Remove or minimise exposure to known allergens (dust, pets, occupational triggers).
• 💊 Pharmacological:
  • Allergic rhinitis: Antihistamines, intranasal steroids, leukotriene antagonists.
  • Asthma: Stepwise approach (SABA → ICS → LABA, per NICE guidelines).
• 💉 Immunotherapy: Desensitisation for severe allergic rhinitis/asthma with specific allergens.
• ⚡ Anaphylaxis: IM adrenaline, O₂, fluids, antihistamines, steroids; provide adrenaline auto-injector for future.

🧠 Key Teaching Points

• Atopy is a triad: eczema, asthma, allergic rhinitis 🤲🌬️👃.
• Always ask about occupational/environmental exposure when assessing unexplained breathlessness.
• Allergy testing is supportive but history remains the cornerstone of diagnosis.
• Allergic disease is dynamic: many children “grow out” of allergies, while others develop late-onset disease.