What is the treatment for a suspected drug rash?

Treatment of Suspected Drug Rash

The first step in treating a suspected drug rash is immediate discontinuation of the suspected causative medication, followed by appropriate symptomatic treatment based on the severity of the rash. 1

Initial Assessment and Classification

When evaluating a suspected drug rash, consider:

1. Timing: When did the rash appear in relation to drug exposure?
2. Appearance: Distribution, morphology (macular, papular, vesicular, etc.)
3. Associated symptoms: Fever, mucosal involvement, systemic symptoms
4. Severity indicators: Extent of skin involvement, presence of blisters, epidermal detachment

Treatment Algorithm Based on Severity

Mild to Moderate Drug Rash (Limited body surface area, no systemic symptoms)

1. Discontinue the suspected causative drug 1
2. Symptomatic treatment:
   • Topical moderate-potency corticosteroids (e.g., hydrocortisone 1%) applied 1-2 times daily for 1-2 weeks 1, 2
   • Oral antihistamines for pruritus:
     • Non-sedating (daytime): Loratadine 10mg daily
     • Sedating (nighttime): Diphenhydramine 25-50mg or hydroxyzine 25-50mg 1
   • Emollients and moisturizers to keep skin hydrated 1
   • Avoid hot water and skin irritants 1

Moderate to Severe Drug Rash (>30% BSA or with troublesome symptoms)

1. Discontinue the suspected causative drug immediately 1
2. Systemic treatment:
   • Oral corticosteroids: Prednisone 0.5-1 mg/kg/day for 7 days with a weaning dose over 4-6 weeks 1
   • For severe pruritus: Consider gabapentin (900-3600 mg daily) or pregabalin (25-150 mg daily) 1
   • Maintain adequate hydration and nutrition 1

Severe Drug Rash with Systemic Symptoms (DRESS) or Epidermal Detachment (SJS/TEN)

1. Immediate discontinuation of all potential culprit drugs 1
2. Urgent referral to specialized care (dermatology, burn unit, or intensive care) 1
3. Supportive care:
   • IV fluid resuscitation if clinically indicated
   • Careful monitoring of vital signs
   • Wound care for denuded skin
   • Systemic corticosteroids (e.g., methylprednisolone IV) 3, 4
   • Consider SCORTEN score to predict mortality in SJS/TEN 1

Special Considerations

For Anaphylactic Reactions

If the rash is part of an anaphylactic reaction, immediate treatment includes:

• Epinephrine (intramuscular)
• Hydrocortisone (IV or IM): 200mg for adults 1
• Chlorphenamine (IV or IM): 10mg for adults 1

For Acneiform Rash (Common with EGFR inhibitors)

• Oral antibiotics for 6 weeks (doxycycline 100 mg b.i.d., minocycline 50 mg b.i.d., or oxytetracycline 500 mg b.i.d.) 1
• Topical low/moderate potency steroids 1
• For grade ≥3: Interrupt causative drug and add systemic corticosteroids 1

Prevention of Rebound Flares After Steroid Discontinuation

For patients requiring systemic steroids, prevent rebound flares by:

1. Maintaining the effective dose for 2-3 weeks before tapering 5
2. Implementing a slow taper over 3 months for severe cases 5
3. Introducing antihistamines or other anti-inflammatory treatments toward the end of the taper 5

Follow-up and Documentation

1. Document all details of the reaction and suspected drugs
2. Consider referral to an allergy specialist for future drug selection 1
3. Provide the patient with information about the culprit drug to avoid future exposure

Common Pitfalls to Avoid

• Continuing the suspected drug: This can worsen the reaction and lead to more severe outcomes 1
• Tapering steroids too quickly: This can cause rebound flares 5
• Overlooking potential cross-reactivity: Be cautious when selecting alternative medications 6
• Missing signs of severe reactions: Watch for mucosal involvement, blistering, or systemic symptoms that may indicate life-threatening conditions like SJS/TEN or DRESS 7

By following this approach, most drug rashes can be effectively managed while minimizing the risk of progression to more severe reactions.