Residency · Residency · Family Medicine

Common Pediatric Rashes and Exanthems

Overview

Skin conditions account for a significant proportion of pediatric primary care visits. Family physicians must accurately recognize common pediatric rashes, distinguish benign from serious conditions, and manage inflammatory skin diseases. Visual pattern recognition combined with systematic evaluation ensures appropriate diagnosis and treatment.

Viral Exanthems

Measles (Rubeola)

Measles is rare in vaccinated populations but outbreaks continue to occur in under-immunized communities. The prodrome includes high fever, cough, coryza, and conjunctivitis, known as the "3 Cs." Koplik spots, pathognomonic for measles, are blue-white papules on the buccal mucosa opposite the molars and appear 2 days before the rash. The rash itself is erythematous and maculopapular, starting at the hairline and face and spreading cephalocaudally over 3 to 4 days. Complications include pneumonia, encephalitis, and subacute sclerosing panencephalitis. Measles is a reportable disease requiring isolation until 4 days after rash onset.

Rubella (German Measles)

Rubella presents as a mild illness with a fine pink maculopapular rash starting on the face and spreading downward. Forchheimer spots, which are petechiae on the soft palate, may be present. Posterior auricular and postoccipital lymphadenopathy is characteristic. The greatest concern is congenital rubella syndrome if maternal infection occurs in the first trimester. The illness is usually self-limited with no specific treatment required.

Roseola (Exanthem Subitum / Sixth Disease)

Roseola is caused by HHV-6 (most commonly) or HHV-7 and typically affects children aged 6 months to 2 years. It presents with high fever, often exceeding 40 degrees Celsius, for 3 to 5 days while the child appears well. The rash appears as the fever breaks, presenting as a diffuse pink, blanchable, maculopapular eruption starting on the trunk and spreading peripherally. Febrile seizures may occur during the high fever phase. No treatment is needed, as the condition is self-limited.

Erythema Infectiosum (Fifth Disease)

Fifth disease is caused by parvovirus B19 and classically presents with the "slapped cheek" appearance: bright red bilateral facial erythema sparing the nose. This is followed by a lacy, reticular rash on the trunk and extremities that waxes and wanes with heat, sun, and bathing. The child is no longer contagious once the rash appears. Complications include aplastic crisis in patients with sickle cell disease and hydrops fetalis if maternal infection occurs during pregnancy. The illness is self-limited and managed with supportive care.

Hand, Foot, and Mouth Disease (HFMD)

HFMD is most commonly caused by Coxsackievirus A16 or Enterovirus 71. It presents with low-grade fever, malaise, and sore throat, followed by oral vesicles and ulcers on the tongue, buccal mucosa, and palate that can be painful and may reduce oral intake. A vesicular rash appears on the palms, soles, and buttocks, and may extend to the knees and elbows. Onychomadesis, or nail shedding, may occur weeks after the acute illness. The condition is self-limited over 7 to 10 days and managed with pain control and hydration.

Varicella (Chickenpox)

Varicella has become increasingly rare due to vaccination. Following a prodrome of low-grade fever and malaise, the characteristic rash develops as pruritic vesicles on an erythematous base described as a "dewdrop on a rose petal." Lesions appear in crops at various stages, with macules, papules, vesicles, and crusts present simultaneously. Distribution is centripetal, starting on the trunk and spreading to the face and extremities. Complications include secondary bacterial skin infection (the most common), pneumonia, cerebellar ataxia, and encephalitis. Treatment is supportive, with acyclovir reserved for high-risk patients including adolescents, immunocompromised individuals, and those with chronic skin disease.

Bacterial Skin Infections

Impetigo

Non-bullous impetigo is the most common form, caused by S. aureus or Group A Streptococcus, presenting as honey-crusted lesions on the face, especially around the nose and mouth. Bullous impetigo is caused by S. aureus toxin and produces flaccid bullae that rupture leaving shallow erosions; it is more common in infants. Treatment includes topical mupirocin or retapamulin for localized disease, with oral antibiotics (cephalexin or dicloxacillin) for extensive disease. MRSA coverage with TMP-SMX or clindamycin is added when concern exists.

Cellulitis

Cellulitis presents as a warm, erythematous, edematous, tender plaque without defined borders. S. aureus and Group A Streptococcus are the most common causes. Marking the borders with a pen helps monitor progression. Treatment consists of oral cephalexin or dicloxacillin, with MRSA coverage added as indicated using TMP-SMX or doxycycline (for age 8 and above). Periorbital cellulitis must be distinguished from orbital cellulitis, which presents with proptosis, ophthalmoplegia, and pain with eye movement and requires hospitalization with IV antibiotics.

Scarlet Fever

Scarlet fever results from Group A Streptococcal pharyngitis with a toxin-mediated rash. The rash has a characteristic sandpaper texture, is erythematous, begins on the neck and trunk, and is accentuated in skin folds (Pastia lines). Strawberry tongue (progressing from white to red) and circumoral pallor are classic findings. Treatment is the same as for GAS pharyngitis with penicillin or amoxicillin, which prevents rheumatic fever.

Fungal Infections

Tinea Corporis (Ringworm)

Tinea corporis presents as an annular, scaly, erythematous plaque with central clearing and a raised advancing border. Diagnosis is confirmed with KOH preparation showing branching hyphae. Treatment uses topical antifungals (terbinafine, clotrimazole, or miconazole) for 2 to 4 weeks. Topical steroids alone should be avoided, as they produce tinea incognito, masking the infection.

Tinea Capitis

Tinea capitis is the most common dermatophyte infection in children and is caused primarily by Trichophyton tonsurans in North America. It presents with scaling patches on the scalp with broken-off hairs ("black dot" appearance) and may develop a kerion, which is an inflammatory boggy mass. Posterior cervical lymphadenopathy is common. Oral antifungal therapy is required because topical agents do not penetrate the hair follicle. Griseofulvin at 20 to 25 mg/kg/day for 6 to 8 weeks is the traditional first-line, while terbinafine is increasingly preferred because of shorter course duration with weight-based dosing for 4 weeks. Selenium sulfide or ketoconazole shampoo serves as an adjunct to reduce transmission. Children may attend school during treatment.

Tinea Pedis

Tinea pedis is less common in prepubertal children and more common in adolescents. It presents with interdigital scaling and maceration or moccasin-type scaling of the soles. Treatment uses topical antifungals for 2 to 4 weeks.

Atopic Dermatitis (Eczema)

Diagnosis

Atopic dermatitis is a clinical diagnosis based on pruritus (which is essential), a chronic or relapsing course, typical distribution, and personal or family history of atopy. In infants, it affects the face, scalp, and extensor surfaces. In children, it shifts to flexural surfaces including the antecubital and popliteal fossae, neck, and wrists. In adolescents and adults, it involves the hands, flexural areas, and face and neck.

Management (Stepwise)

Step 1 focuses on skin care basics: daily lukewarm baths of 5 to 10 minutes followed by immediate moisturizer application ("soak and seal"), use of fragrance-free emollients (with ointments superior to creams, which are superior to lotions in occlusive ability), and avoidance of irritants such as harsh soaps, fragrances, wool, and excessive heat. Step 2 involves topical corticosteroids: mild potency (hydrocortisone 1 to 2.5%) for the face, skin folds, and infants; medium potency (triamcinolone 0.1%) for the body; and high potency (fluocinonide 0.05%) for thick plaques on the extremities for short durations. These are applied to active lesions while moisturizer continues on uninvolved skin. Proactive therapy involves applying low-potency TCS twice weekly to frequently affected areas to prevent flares. Step 3 uses topical calcineurin inhibitors: tacrolimus 0.03% and pimecrolimus for ages 2 and above. These are steroid-sparing and safe for the face and skin folds. The FDA black box warning for theoretical cancer risk is not supported by clinical evidence. Step 4 introduces topical PDE4 inhibitor crisaborole for ages 3 months and above for mild to moderate disease. Step 5 uses topical JAK inhibitor ruxolitinib for ages 12 and above for short-term use in mild to moderate disease. Step 6 involves systemic therapy requiring dermatology referral, including dupilumab (anti-IL-4/IL-13, FDA-approved for ages 6 months and above, first-line systemic for moderate to severe disease), other biologics such as tralokinumab, JAK inhibitors (abrocitinib and upadacitinib for ages 12 and above), and traditional agents such as cyclosporine, methotrexate, and azathioprine, which are used less frequently now.

Comorbidities

Eczema herpeticum is an HSV superinfection presenting with widespread vesicles or punched-out erosions that requires urgent acyclovir. Molluscum contagiosum is more common and widespread in atopic dermatitis. Bacterial superinfection with S. aureus colonizes 90% of atopic dermatitis skin. Sleep disruption from pruritus is common. Food allergy evaluation should be considered if severe atopic dermatitis is unresponsive to therapy, especially in infants.

Diaper Dermatitis

Irritant contact dermatitis is the most common form, presenting with erythema on convex surfaces while sparing the creases, managed with barrier cream (zinc oxide or petrolatum) and frequent diaper changes. Candidal diaper dermatitis presents with beefy red erythema with satellite papules and pustules involving the creases, treated with topical nystatin or clotrimazole. Seborrheic dermatitis presents with salmon-colored patches with greasy scale and may overlap with cradle cap on the scalp.

Urticaria

Urticaria presents as raised, erythematous, pruritic wheals that blanch with pressure. Individual lesions last less than 24 hours; if they persist longer, urticarial vasculitis should be considered. Acute urticaria (lasting fewer than 6 weeks) is most common in children and is often triggered by viral illness, less commonly by food or drug allergy. Chronic urticaria (lasting more than 6 weeks) is usually autoimmune or idiopathic. Treatment uses second-generation antihistamines such as cetirizine and loratadine, with first-generation agents avoided in young children when possible. Assessment for anaphylaxis is essential when urticaria is accompanied by respiratory symptoms, hypotension, or gastrointestinal symptoms.

When to Worry: Red Flag Rashes

Non-blanching petechiae or purpura should raise concern for meningococcemia, ITP, HSP, DIC, or leukemia. Target lesions with mucosal involvement suggest Stevens-Johnson syndrome or toxic epidermal necrolysis. Widespread blistering in a febrile, ill-appearing child suggests staphylococcal scalded skin syndrome. Expanding erythema with central clearing after a tick bite indicates erythema migrans from Lyme disease. A desquamating rash with fever, conjunctivitis, strawberry tongue, and extremity changes suggests Kawasaki disease, which requires urgent echocardiography and IVIG.

<image>A visual atlas of common pediatric viral exanthems showing characteristic rash morphology and distribution for measles (cephalocaudal maculopapular with Koplik spots), roseola (trunk-predominant after fever resolution), fifth disease (slapped cheek with reticular body rash), hand-foot-and-mouth disease (oral vesicles with palmar/plantar lesions), and varicella (crops in various stages, centripetal distribution).</image>

<image>A stepwise management algorithm for pediatric atopic dermatitis showing the treatment ladder from basic skin care (emollients, bathing practices) through topical corticosteroids (organized by potency and body location), calcineurin inhibitors, PDE4 inhibitors, and systemic therapies (dupilumab, JAK inhibitors), with criteria for stepping up and referral to dermatology.</image>

<image>A comparison guide for pediatric diaper rashes showing side-by-side images and descriptions of irritant contact dermatitis (convex surfaces, spares creases), candidal diaper dermatitis (beefy red with satellite lesions, involves creases), and seborrheic dermatitis (greasy salmon-colored patches), with first-line treatment for each type.</image>

Clinical Pearls

Roseola classically presents with high fever for 3 to 5 days in a well-appearing child followed by rash as the fever breaks; the rash does not require treatment and the diagnosis is reassuring. In fifth disease caused by parvovirus B19, the child is no longer contagious once the rash appears, and school exclusion is unnecessary unless the child is immunocompromised or has a hemoglobinopathy. Tinea capitis requires oral antifungal therapy because topical antifungals alone do not penetrate the hair follicle and will fail. "Topical steroid phobia" is common among parents and leads to undertreated eczema; concerns should be addressed proactively with an explanation that appropriate use of topical steroids is safe and prevents disease progression. Any non-blanching petechial or purpuric rash in a febrile child requires urgent evaluation for meningococcemia and other serious infections. Eczema herpeticum presents as monomorphic punched-out erosions or vesicles and requires urgent systemic acyclovir; it should not be confused with bacterial superinfection. Kawasaki disease should be considered in any child with fever of 5 days or longer plus 4 of 5 clinical criteria (conjunctivitis, oral changes, rash, extremity changes, cervical lymphadenopathy), and early treatment with IVIG reduces coronary artery aneurysm risk. When in doubt, a KOH preparation should be performed for any scaly, annular, or asymmetric rash to rule out fungal infection before prescribing topical steroids.

References

• Eichenfield LF et al. AAD Guidelines of Care for Atopic Dermatitis. J Am Acad Dermatol. 2014
• Paller AS et al. Dupilumab in Children 6 Months to 5 Years with Atopic Dermatitis. Lancet. 2022
• Cherry JD. Measles Virus. In: Cherry JD et al, eds. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th ed. 2019
• AAP Red Book: Report of the Committee on Infectious Diseases. 33rd ed. 2024
• Morelli JG. Diseases of the Skin. In: Kliegman RM et al, eds. Nelson Textbook of Pediatrics. 21st ed. 2020

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