What is the treatment for a pruritic rash appearing after an insect bite?

Treatment for Pruritic Rash After Insect Bite

For pruritic rash appearing after an insect bite, topical hydrocortisone cream is the first-line treatment, applied to the affected area up to 3-4 times daily. 1

Initial Management

1. Clean the area:

   • Wash the bite area with mild soap and water to reduce pain and swelling 2
   • Gently dry by patting or blotting with a soft cloth 1

2. First-line treatment:

   • Apply topical hydrocortisone cream (0.5-1%) to the affected area up to 3-4 times daily 1
   • For mild-to-moderate pruritus, consider topical preparations containing:
     • Menthol 0.5% 3
     • Mometasone furoate 0.1% ointment or betamethasone valerate 0.1% ointment 3

3. Oral antihistamines:

   • For daytime use: Non-sedating second-generation antihistamines such as loratadine (10 mg daily) or fexofenadine (180 mg daily) 3
   • For nighttime use: First-generation antihistamines such as diphenhydramine (25-50 mg) or hydroxyzine (25-50 mg) 3

For Persistent or Severe Symptoms

If symptoms persist despite initial management:

1. Systemic treatments to consider:

   • Oral corticosteroids (0.5-2 mg/kg daily) for temporary relief of particularly severe pruritus 3
   • Antiepileptic agents as second-line treatment:
     • Pregabalin (25-150 mg daily)
     • Gabapentin (900-3600 mg daily) 3

2. Other potential options:

   • Doxepin (tricyclic antidepressant with potent antihistamine properties) 3
   • Aprepitant (neurokinin-1 receptor antagonist) for refractory cases 3

Special Considerations

• Preventive measures:

  • Wear protective clothing (long pants, long sleeves, closed shoes) 2
  • Use insect repellents containing DEET 2
  • Apply permethrin spray on clothing 2

• When to seek medical attention:

  • Signs of infection (increasing redness, warmth, swelling, or purulent discharge)
  • Fever or systemic symptoms
  • Rash spreading beyond the bite area
  • Symptoms of anaphylaxis (difficulty breathing, swelling of face/throat, dizziness) 2

Cautions

• Long-term use of sedative antihistamines may predispose to dementia and should be avoided except in palliative care 3
• Topical crotamiton cream is not recommended for generalized pruritus 3
• Topical capsaicin or calamine lotion is not recommended for generalized pruritus 3

The management approach should focus on symptom relief while monitoring for potential complications. Most insect bite reactions are self-limiting and resolve with simple topical treatments, but persistent or severe symptoms may require more aggressive management.