🤧 Allergic disorders are conditions caused by an exaggerated immune response to normally harmless substances called allergens. They are highly prevalent worldwide and account for a major burden of chronic disease, especially in children and young adults. Reactions can be mild (hay fever, eczema) or severe and life-threatening (anaphylaxis). Early recognition, prevention, and appropriate management are crucial. 🚨

🧬 Physiology & Pathophysiology of Allergy

Immune sensitisation: On first exposure, allergens are processed by antigen-presenting cells and presented to Th2 helper T cells, which release cytokines (IL-4, IL-5, IL-13).
IgE production: B cells switch to produce allergen-specific IgE antibodies under Th2 influence. These IgE molecules bind to mast cells and basophils.
Re-exposure: When the allergen is encountered again, it cross-links IgE on mast cells → degranulation.
Mediators released: Histamine, leukotrienes, prostaglandins, and cytokines → cause vasodilation, increased vascular permeability, smooth muscle contraction, and mucus secretion.
Clinical outcomes: Sneezing, wheezing, itching, urticaria, angioedema, or systemic anaphylaxis depending on the site and severity of reaction.

💡 In essence: Allergy = IgE + mast cell activation. Repeated exposure = more vigorous response → chronic inflammation (e.g. asthma, eczema).

🌿 Common Types of Allergic Disorders


Disorder	Definition	Symptoms	Triggers	Management
Allergic Rhinitis (Hay Fever) 🌸	Inflammation of nasal passages due to allergens.	Sneezing, itchy/runny nose, watery eyes.	Pollen, dust mites, pets, mold.	Antihistamines, nasal steroids, allergen avoidance, immunotherapy.
Asthma 😮‍💨	Chronic airway inflammation with reversible obstruction.	Wheeze, cough, chest tightness, breathlessness.	Allergens, cold air, exercise, stress.	Inhaled steroids, bronchodilators, leukotriene inhibitors.
Atopic Dermatitis (Eczema) 🧴	Chronic inflammatory skin condition.	Dry, red, itchy patches (hands, neck, flexures).	Soaps, detergents, allergens, stress.	Moisturizers, topical steroids, avoid irritants.
Urticaria (Hives) 🔴	Transient raised itchy welts on skin.	Red, itchy, swollen patches.	Foods, medications, infections, stress.	Antihistamines, short course steroids (severe).
Food Allergies 🍤🥜	Immune reaction to food proteins.	Hives, facial swelling, GI upset, anaphylaxis.	Peanuts, shellfish, eggs, milk, wheat, soy.	Avoidance, antihistamines, epinephrine for anaphylaxis.
Drug Allergies 💊	Immune response to medications.	Rash, itching, swelling, anaphylaxis.	Penicillin, sulfa drugs, NSAIDs.	Stop drug, antihistamines, steroids, epinephrine if severe.
Anaphylaxis 🚨	Severe systemic allergic reaction.	Airway swelling, wheeze, shock, collapse.	Foods, insect stings, medications, latex.	Immediate epinephrine + emergency care.

🔍 Diagnostic Approach

🩹 Skin Prick Tests: Immediate hypersensitivity testing.
🧪 IgE Blood Tests: Specific allergen IgE levels.
🥗 Elimination Diets: For food allergy confirmation.
⚠️ Challenge Tests: Under medical supervision only.

💊 Treatment & Management

🚫 Avoidance: Best prevention strategy.
💊 Medications: Antihistamines, corticosteroids, leukotriene inhibitors.
💉 Immunotherapy: Gradual desensitisation (allergy shots or tablets).
⚡ Epinephrine: First-line for anaphylaxis, must be carried by high-risk patients.

🚨 Red Flags

⚡ Anaphylaxis: Immediate epinephrine and 999 call.
😮‍💨 Severe asthma attack: Not relieved by inhalers → urgent hospital care.
📈 Sudden worsening symptoms: New or rapidly progressing → emergency review.

✅ Summary: Allergies result from IgE-mediated immune overreaction. They range from mild rhinitis to life-threatening anaphylaxis. Medical students should understand both mechanisms and clinical presentations, as prompt recognition and treatment save lives.

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Allergic disorders

🧬 Physiology & Pathophysiology of Allergy

🌿 Common Types of Allergic Disorders

🔍 Diagnostic Approach

💊 Treatment & Management

🚨 Red Flags

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