Allergic Reactions

Allergic Reactions – Treatment Overview

Introduction
Allergic reactions are exaggerated immune responses to otherwise harmless substances (allergens) such as foods, medications, insect stings, or environmental triggers. They range in severity from mild (itching, rash, sneezing) to life-threatening (anaphylaxis). The main goals of management are to remove the allergen, alleviate symptoms, and prevent recurrence or complications. Treatment varies depending on the severity of the reaction.

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Treatment Options and Doses

1. Mild Allergic Reactions (rash, itching, sneezing, watery eyes)

• Antihistamines (H1 blockers):

  • Cetirizine: 10 mg orally once daily.

  • Loratadine: 10 mg orally once daily.

  • Diphenhydramine: 25–50 mg orally or IV every 6–8 hours as needed (sedating).

• Topical corticosteroids (for localized rash):

  • Hydrocortisone 1% cream: Apply thinly 1–2 times daily.

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2. Moderate Allergic Reactions (more widespread rash, swelling, mild breathing difficulty)

• Oral corticosteroids (short course):

  • Prednisolone: 0.5–1 mg/kg/day orally for 3–5 days, taper as needed.

• H2 receptor blockers (as adjunct):

  • Ranitidine (where available): 150 mg orally twice daily.

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3. Severe Allergic Reactions (Anaphylaxis)

• Epinephrine (first-line, life-saving):

  • Adults: 0.3–0.5 mg intramuscularly (IM) into the mid-thigh.

  • Children: 0.01 mg/kg IM (maximum 0.3 mg per dose).

  • Repeat every 5–15 minutes if needed.

• Oxygen therapy and IV fluids for circulatory support.

• Adjunctive therapy after epinephrine:

  • Antihistamines (H1 + H2 blockers).

  • Corticosteroids: Methylprednisolone 1–2 mg/kg IV to reduce risk of biphasic reaction.

  • Salbutamol nebulization for bronchospasm if present.

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4. Long-Term Management and Prevention

• Allergen avoidance (foods, medications, insect bites, environmental triggers).

• Epinephrine auto-injector (e.g., EpiPen): Prescribed for patients at risk of recurrent anaphylaxis.

• Allergen immunotherapy (desensitization): For selected patients with persistent allergic rhinitis, asthma, or insect sting allergy.