What are the causes, types, and management of rashes in infants?

Rashes in Infants: Etiology, Types, and Management

Immediate Life-Threatening Considerations

If an infant presents with fever and rash, immediately assess for meningococcemia or serious bacterial infection, as these can be rapidly fatal and require urgent intervention. 1

• Petechial or purpuric rash with fever is a medical emergency requiring immediate blood cultures and empiric antibiotics (intramuscular ceftriaxone) pending culture results 1
• Signs requiring immediate hospitalization include: toxic appearance, hypotension, altered mental status, respiratory distress, or age <28 days with any fever 1
• Extensive blistering suggesting staphylococcal scalded skin syndrome (SSSS) or mucosal involvement suggesting Stevens-Johnson syndrome require immediate hospital admission 1

Common Benign Neonatal Rashes (Self-Limited)

Erythema Toxicum Neonatorum

• Presents as erythematous macules, papules, and pustules on face, trunk, and extremities 2, 3
• Typically resolves spontaneously within 1 week without treatment 2, 3
• Parental reassurance and observation are sufficient 2

Neonatal Acne (Acne Neonatorum)

• Presents as comedones or erythematous papules on face, scalp, chest, and back 3
• Typically resolves spontaneously; failure to resolve within 1 year warrants evaluation for androgen excess 3
• Neonatal cephalic pustulosis (acne variant caused by Malassezia furfur) is typically self-limited but severe cases may require topical ketoconazole 3

Transient Neonatal Pustular Melanosis

• A transient vesiculopustular rash that can be diagnosed clinically based on distinctive appearance 2
• Requires no treatment and resolves spontaneously 2

Milia and Miliaria

• Result from immaturity of skin structures 2
• Present as tiny vesicles or papules that resolve spontaneously 3
• Miliaria rubra (heat rash) improves after cooling measures (removing excess clothing, maintaining cool environment) 2

Common Inflammatory/Infectious Rashes Requiring Treatment

Seborrheic Dermatitis

• Extremely common, causing scaling on the scalp (cradle cap) 2, 3
• Management algorithm:
  • First-line: Shampooing and removing scales with soft brush after applying mineral oil or petrolatum 3
  • Severe/persistent cases: Tar-containing shampoo, topical ketoconazole, or mild topical steroids 2
• Must be distinguished from atopic dermatitis 2

Diaper Dermatitis

Contact Diaper Dermatitis (Irritant)

• Managed by keeping diaper area clean with frequent diaper changes and open air exposure 3
• Avoid using hydrocortisone for diaper rash treatment 4

Candidal Diaper Dermatitis

• Presents with satellite lesions and involvement of skin folds 3
• Managed with topical antifungal agents 3
• Critical pitfall: Do not assume benign diagnosis based solely on "diaper rash" appearance—many serious conditions can present with rash in the diaper area 1

Atopic Dermatitis

• A chronic, relapsing inflammatory skin condition with variety of skin changes 5
• Related to food allergy in approximately one-third of children 3
• Management algorithm:
  • Eliminate irritants and triggers 3
  • Use low-potency topical steroids (hydrocortisone 2.5% for children ≥2 years, applied 3-4 times daily) 4
  • Consider food allergy testing (oral food challenges or skin prick tests) if suspected 3

Viral Exanthems

Roseola (Human Herpesvirus 6)

• Distinguishing feature: 3-4 days of high fever followed by rash as fever resolves 1
• Most likely diagnosis when rash appears after fever breaks 1
• Self-limited; requires only supportive care 5

Enteroviral Infections

• Can cause fever with vesicular rash 1
• Palms and soles involvement may occur 1
• Generally self-limited 5

Erythema Infectiosum (Fifth Disease)

• Characterized by viral prodrome followed by "slapped cheek" facial rash 5
• May be associated with pruritus 5
• Self-limited; supportive care only 5

Critical Physical Examination Findings for Risk Stratification

Assess these specific features to differentiate benign from serious conditions:

• Location: Palms and soles involvement suggests serious infection (RMSF) or viral exanthem; diaper area alone suggests irritant dermatitis or candidiasis 1
• Lesion type: Flaccid blisters suggest SSSS; tense blisters suggest other causes; target lesions suggest Stevens-Johnson syndrome 1
• Mucous membranes: Oral, conjunctival, or genital erosions suggest Stevens-Johnson syndrome 1
• Petechiae/purpura: Suggests meningococcemia or serious bacterial infection requiring immediate intervention 1

Diagnostic Workup for Febrile Infant with Rash

Immediate laboratory evaluation:

• Complete blood count with differential, C-reactive protein, comprehensive metabolic panel 1
• Blood culture before antibiotics 1
• Urinalysis and urine culture (urinary tract infections cause >90% of serious bacterial illness in this age group) 1

Additional testing based on clinical presentation:

• If unusual presentation or signs of systemic illness: evaluate for Candida, viral, and bacterial infections 2
• Serological and PCR assays can help differentiate viral exanthem from drug hypersensitivity, though concomitant infection does not exclude drug reaction 6

Management of Specific Conditions

Topical Steroid Use (Hydrocortisone)

FDA-approved indications for children ≥2 years: 4

• Itching associated with minor skin irritations, inflammation, and rashes due to: eczema, psoriasis, poison ivy/oak/sumac, insect bites, detergents, jewelry, cosmetics, soaps, seborrheic dermatitis
• Apply to affected area 3-4 times daily 4
• Contraindications: Do not use for diaper rash treatment 4
• Avoid contact with eyes and do not use more than directed 4

When Systemic Antibiotics Are Needed

• Suspected meningococcemia: immediate intramuscular ceftriaxone 1
• Impetigo (superficial bacterial infection commonly affecting face and extremities): topical or systemic antibiotics depending on extent 5

Common Pitfalls to Avoid

• Do not rely on fever response to antipyretics to exclude serious bacterial infection—fever response does not reliably predict bacterial versus viral etiology 1
• Do not assume geographic safety from serious tickborne illness—consider endemic diseases throughout the United States 1
• Do not wait for positive serology to treat suspected serious infections—early serology is typically negative 1
• Do not confuse viral exanthem with drug allergy—viral exanthema is perceived as drug allergy in 10% of cases, particularly when medications (beta-lactams, NSAIDs) are given during viral infections 6
• Do not overlook food allergy in atopic dermatitis—approximately one-third of children with atopic dermatitis have associated food allergy 3

Disposition Algorithm

Admit to hospital if: 1

• Child appears toxic or has signs of sepsis
• Extensive blistering suggesting SSSS
• Mucosal involvement suggesting Stevens-Johnson syndrome
• Suspected meningococcemia with systemic symptoms
• Age <28 days with any fever

Outpatient management appropriate for:

• Benign neonatal rashes (erythema toxicum, milia, miliaria) with parental reassurance 2
• Mild seborrheic dermatitis or contact diaper dermatitis with topical management 3
• Viral exanthems in well-appearing children without concerning features 5