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.

🤧 Case Examples — Allergy

• Case 1: 🌸 A 15-year-old girl develops recurrent sneezing, watery rhinorrhoea, and itchy eyes each spring during exam season. Symptoms are worse when outdoors and improve with antihistamines. Diagnosis: Seasonal allergic rhinitis (hay fever). She is managed with oral antihistamines, topical nasal steroids, and allergen avoidance, with good symptom control during pollen season.
• Case 2: 🥜 A 22-year-old man eats a peanut-containing snack and within minutes develops lip swelling, urticaria, and throat tightness. He collapses before reaching hospital. Diagnosis: Anaphylaxis triggered by peanut allergy. He receives immediate intramuscular adrenaline, high-flow oxygen, IV fluids, and antihistamines, with rapid improvement. He is discharged with an adrenaline auto-injector and referred to an allergy clinic for testing and long-term management.
• Case 3: 💊 A 55-year-old woman is prescribed amoxicillin for a chest infection. Two days later she develops a widespread pruritic maculopapular rash and facial swelling but no airway compromise. Diagnosis: Allergic drug reaction to penicillin. The antibiotic is discontinued, she is treated with antihistamines and corticosteroids, and the allergy is documented in her medical record. She is referred for formal penicillin allergy testing.