====== Drugs For Allergy  ======

**Focus:** Histamine signaling and pharmacologic management of allergic disease.  
Organized by drug class with clinical treatment references below.

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===== H1 Antihistamines — First Generation (Sedating) =====

  * [[allergy:drugs:brompheniramine|Brompheniramine]]
  * [[allergy:drugs:chlorpheniramine|Chlorpheniramine]]
  * [[allergy:drugs:diphenhydramine|Diphenhydramine]]
  * [[allergy:drugs:hydroxyzine|Hydroxyzine]]
  * [[allergy:drugs:promethazine|Promethazine]]
  * [[allergy:drugs:dimenhydrinate|Dimenhydrinate]]
  * [[allergy:drugs:meclizine|Meclizine]]

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===== H1 Antihistamines — Second Generation (Non-Sedating) =====
[[allergy:drug_classes:second_generation_h1|Second Generation Histamine-1 Antagonists]]
  * [[allergy:drugs:fexofenadine|Fexofenadine]]
  * [[allergy:drugs:loratadine|Loratadine]]
  * [[allergy:drugs:cetirizine|Cetirizine]]
  * [[allergy:drugs:levocetirizine|Levocetirizine]]
  * [[allergy:drugs:desloratadine|Desloratadine]]

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===== H2 Blockers =====

  * [[gi:drugs:cimetidine|Cimetidine]]
  * [[gi:drugs:famotidine|Famotidine]]
  * [[gi:drugs:nizatidine|Nizatidine]]
  * Ranitidine (off market)

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===== Mast Cell Stabilizers =====
  * [[allergy:drugs:cromolyn|Cromolyn Sodium]]
  * Nedocromil (off market)

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===== Leukotriene Pathway Modifiers =====
[[respiratory:drug_classes:leukotriene_modifiers|Leukotriene Modifiers]]
  * [[respiratory:drugs:montelukast|Montelukast]]
  * [[respiratory:drugs:zafirlukast|Zafirlukast]]
  * [[respiratory:drugs:zileuton|Zileuton]]

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===== Corticosteroids in Allergy =====
[[endocrine:drug_classes:Corticosteroids]]
==== Intranasal ====
  * [[endocrine:drugs:fluticasone|Fluticasone]]
  * [[endocrine:drugs:mometasone|Mometasone]]
  * [[endocrine:drugs:budesonide|Budesonide]]

==== Systemic ====
  * [[endocrine:drugs:prednisone|Prednisone]]
  * [[endocrine:drugs:methylprednisolone|Methylprednisolone]]

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===== Rescue Therapy =====

  * [[cardio:drugs:epinephrine|Epinephrine]]

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===== Biologic Therapies For Allergy =====

  * [[immunology:drugs:omalizumab|Omalizumab]]
  * [[immunology:drugs:mepolizumab|Mepolizumab]]
  * [[immunology:drugs:reslizumab|Reslizumab]]
  * [[immunology:drugs:benralizumab|Benralizumab]]
  * [[immunology:drugs:dupilumab|Dupilumab]]

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===== Clinical Use =====
**Use this section when you’re starting from the patient presentation.**

  * **Allergic Rhinitis** → [[allergy:clinical:allergic_rhinitis|Treatment & Stepwise Therapy]]  
    (Intranasal steroid first-line; add antihistamine based on symptoms)
  * **Urticaria / Pruritus** → [[allergy:clinical:urticaria_angioedema|Treatment Approach]]  
    (Scheduled 2nd-gen H1 blockers; escalate; chronic urticaria options)
  * **Angioedema** → [[allergy:clinical:urticaria_angioedema|Histamine vs Bradykinin Angioedema]]  
    (Distinguish allergic vs ACEi/HAE)
  * **Anaphylaxis** → [[allergy:clinical:anaphylaxis|Emergency Algorithm]]  
    (IM epinephrine first-line; adjuncts second)
  * **Asthma overlap / AERD** → [[respiratory:asthma:allergic_asthma|Allergic Asthma + Leukotrienes]]  

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===== Mechanisms =====
**Use this section when you’re starting from physiology/pathophysiology.**

  * [[allergy:histamine:histamine_physiology|Histamine Physiology (Synthesis, Storage, Release)]]
  * [[allergy:histamine:histamine_receptors|Histamine Receptors (H1–H4) & G-Protein Signaling]]
  * [[allergy:immunology:type_i_hypersensitivity|Type I Hypersensitivity (IgE → Mast Cell → Early/Late Phase)]]
  * [[allergy:immunology:hypersensitivity_types|Hypersensitivity Types I–IV (Drug Rash Mapping)]]
  * [[allergy:histamine:eicosanoids_inflammation|Eicosanoids, Leukotrienes, Prostaglandins (Inflammation Link)]]

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===== Learning Tools =====
  * [[allergy:histamine:quiz|Quiz: Histamine & Antihistamines]]
  * [[allergy:histamine:cases|Case Bank (Rhinitis, Urticaria, Anaphylaxis)]]
  * [[allergy:histamine:algorithms|One-Page Algorithms (High Yield)]]
  * [[allergy:histamine:crossword|Crossword Puzzle]]
  * [[allergy:histamine:crossword_answers|Crossword Answers]]

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===== Notes =====
  * **Board pearl:** 1st-gen H1 blockers cross the BBB → sedation + anticholinergic toxicity (esp. elderly).
  * **Clinical pearl:** Angioedema without hives raises concern for bradykinin-mediated etiologies (ACEi/HAE).