What is the appropriate management for a patient presenting with a rash?

Management of Rash in Adults

The appropriate management of a rash depends critically on identifying life-threatening causes first, then categorizing by morphology (petechial/purpuric, erythematous, maculopapular, or vesiculobullous) and associated features (fever, body surface area involvement, pruritus) to guide specific treatment.

Initial Assessment and Red Flags

Immediately assess for life-threatening conditions that require urgent intervention:

• Examine for petechiae/purpura with fever suggesting meningococcemia or other severe bacterial infections requiring immediate antibiotics 1
• Look for bullous lesions, skin sloughing, or mucosal involvement indicating Stevens-Johnson syndrome/toxic epidermal necrolysis 2, 3
• Check for widespread erythema with systemic toxicity suggesting toxic shock syndrome or drug reaction with eosinophilia and systemic symptoms (DRESS) 2, 4
• Assess body surface area (BSA) involvement, as >30% BSA with symptoms indicates severe toxicity requiring hospitalization 2

History and Physical Examination Essentials

Obtain specific details that narrow the differential:

• Recent medication changes (especially within 1-2 weeks), as drug reactions are among the most common causes of rash 5, 4
• Travel history to endemic areas for dengue, rickettsial diseases, or viral hemorrhagic fevers 2
• Fever pattern and timing relative to rash onset (fever before rash suggests viral exanthem; rash during fever suggests drug reaction or bacterial infection) 6, 7
• Contact with animals, unpasteurized dairy, or tick exposure for brucellosis, leptospirosis, or rickettsial disease 2
• Immunosuppression status or recent immunotherapy, as immune checkpoint inhibitors cause distinct rash patterns 2

Management by Severity Grade

Grade 1 (Mild): <10% BSA, Well-Tolerated

Continue any causative medications if benefits outweigh risks and treat symptomatically:

• Apply emollients liberally 2-3 times daily, using 30-60g per application for arms or 100g for trunk 2, 3
• Use mild-potency topical corticosteroids: hydrocortisone 1-2.5% for face/groin/genital areas, applied 3-4 times daily 2, 8
• Add non-sedating antihistamines (cetirizine 10mg or loratadine 10mg daily) for pruritus rather than sedating diphenhydramine 9, 5
• Counsel patients to avoid skin irritants, hot water, and harsh soaps 2

Grade 2 (Moderate): 10-30% BSA or Limiting Instrumental Activities

Consider holding causative medications and escalate topical therapy:

• Monitor weekly for progression; if no improvement after 4 weeks, regrade as Grade 3 2
• Apply medium-to-high potency topical corticosteroids: betamethasone valerate 0.1% or mometasone 0.1% to body (avoid face/groin) 2, 3
• Consider initiating oral prednisone 0.5-1 mg/kg/day, tapering over 4 weeks if topical therapy insufficient 2, 9
• Add topical antibiotics (alcohol-free formulations) if signs of superinfection present 2
• Consider oral antibiotics (tetracycline ≥2 weeks) for suspected bacterial superinfection 2

Grade 3 (Severe): >30% BSA with Moderate-Severe Symptoms

Hold all potentially causative medications immediately and initiate systemic therapy:

• Consult dermatology urgently to determine appropriateness of resuming any causative agents 2, 3
• Initiate oral prednisone 1 mg/kg/day, tapering over at least 4-6 weeks 2, 3
• Apply high-potency topical corticosteroids (clobetasol propionate 0.05%) to body only 2
• Consider phototherapy for severe pruritus unresponsive to other measures 2
• For pruritus without visible rash, consider gabapentin, pregabalin, aprepitant, or dupilumab 2

Grade 4 (Life-Threatening): Requiring Hospitalization

Admit immediately with direct oncology/dermatology involvement:

• Administer IV methylprednisolone 1-2 mg/kg with slow taper when toxicity resolves 2
• Monitor closely for progression to severe cutaneous adverse reactions (SCAR) 2, 5
• Consider alternative therapy over resuming causative agents; only restart if patient has no other options and toxicity resolves to Grade 1 2

Special Clinical Scenarios

Fever with Rash in Returned Travelers

Prioritize infectious causes based on geographic exposure:

• Test for dengue (PCR days 1-8) if travel to Southeast Asia/South Central Asia; manage symptomatically as outpatient with daily complete blood count monitoring 2
• Consider rickettsial disease if tick exposure in game parks with headache and fever; treat empirically with doxycycline 2
• Rule out viral hemorrhagic fever if travel to Sub-Saharan Africa with fever, rash, and bleeding; contact regional reference center immediately 2
• Test for acute HIV (antigen and antibody) as seroconversion illness commonly presents with fever and rash 2

Drug-Induced Rash

Discontinue the suspected culprit medication immediately:

• Eczematous drug eruptions can persist for weeks after medication initiation if the allergen continues systemically 5
• Document the reaction as a drug allergy to prevent future exposure 5
• Obtain bacterial swabs if signs of secondary infection (increased warmth, purulence, spreading erythema) present 5, 3
• Apply emollients liberally at least twice daily using alcohol-free, hypoallergenic moisturizers 5

Urticaria (Recurrent Palpable Rash)

Start with oral second-generation non-sedating H1 antihistamines as first-line therapy:

• Trial at least two different non-sedating antihistamines (cetirizine, loratadine, fexofenadine) before declaring treatment failure 9
• If inadequate response, escalate dose up to 4-fold before considering alternative treatments 9
• Avoid NSAIDs completely in aspirin-sensitive urticaria 9
• Do NOT use routine topical corticosteroids, as wheals migrate and last only 2-24 hours 9
• For refractory cases, add omalizumab 300mg every 4 weeks as second-line therapy 9
• Consider cyclosporine 4 mg/kg/day for up to 2 months as third-line for severe autoimmune urticaria 9

Critical Pitfalls to Avoid

• Never use high-potency topical steroids in intertriginous areas (groin, axillae) due to increased risk of skin atrophy; use hydrocortisone 1% instead 5, 3, 8
• Do not apply topical corticosteroids for more than 2-3 weeks without reassessment, as prolonged use causes skin atrophy 2
• Avoid topical retinoids or acne medications in drug-induced eczematous eruptions as they worsen xerosis and irritation 5
• Do not escalate methylprednisolone above 2 mg/kg/day, as there is no benefit to higher doses 9
• Avoid prolonged sedating antihistamines (diphenhydramine) especially in patients who drive or operate machinery 5, 3
• Do not use aspirin in dengue fever due to bleeding risk 2

When to Refer to Dermatology

Refer urgently if:

• Diagnosis remains unclear after initial evaluation and empiric treatment fails 10
• Chronic Grade 2 rash develops with deleterious effect on quality of life 2
• Any bullous, exfoliative, or mucosal features develop 2, 3
• Grade 3 or higher toxicity requiring systemic immunosuppression 2
• Consideration of skin biopsy needed for definitive diagnosis 2, 10