Infantile Seborrhoeic Dermatitis (Cradle Cap)
Summary
Infantile seborrhoeic dermatitis (commonly known as "cradle cap") is a common, benign, self-limiting inflammatory skin condition affecting infants in the first months of life. It presents with greasy, yellowish, scaly patches on the scalp (the classic "cradle cap" appearance), but may also affect the face, ears, nappy area, and skin folds. Crucially, it is non-itchy, which distinguishes it from atopic eczema. The condition is thought to relate to maternal hormonal influence on sebaceous glands and possibly Malassezia yeast. No treatment is required for most cases — simple measures like emollients and gentle brushing are sufficient. It typically resolves spontaneously by 6-12 months of age.
Key Facts
- Definition: Self-limiting inflammatory dermatosis of infancy affecting sebaceous gland-rich areas
- Prevalence: Affects 10% of infants in first 3 months; up to 70% at some point in infancy
- Onset age: Typically 2-8 weeks of life
- Resolution: Usually by 6-12 months (rarely persists beyond 1 year)
- Key feature: NOT itchy (unlike atopic eczema)
- Aetiology: Maternal hormone influence + Malassezia yeast + sebaceous gland overactivity
- Treatment: Usually none required; emollients and gentle scale removal
Clinical Pearls
Not Itchy!: The key differentiator from atopic eczema. Cradle cap does not cause irritability or scratching. If the baby seems uncomfortable or is scratching, reconsider the diagnosis.
"Greasy" vs "Dry": Seborrhoeic dermatitis is greasy and yellowish. Atopic eczema is typically dry and red. This is a simple clinical discriminator.
Nappy Area Overlap: When cradle cap involves the nappy area, it often spares the skin creases (unlike candida which loves creases). The flexural pattern helps differentiate.
Why This Matters Clinically
Cradle cap is extremely common and causes significant parental anxiety, often prompting GP visits. Reassurance that it is harmless and self-limiting is the most important intervention. Distinguishing it from atopic eczema is important because management differs and atopic eczema has prognostic implications (atopic march).
Incidence & Prevalence
- Prevalence at 3 months: Approximately 10%
- Cumulative incidence: Up to 70% of infants have some degree
- Peak age: 2-8 weeks (first 3 months most common)
- Resolution: 90% resolve by 12 months
Demographics
| Factor | Details |
|---|---|
| Age | Onset 2-8 weeks; resolves by 6-12 months |
| Sex | Equal (slight male predominance in some studies) |
| Ethnicity | All ethnic groups |
| Geography | Worldwide, no geographic variation |
Risk Factors
Non-Modifiable:
- Maternal hormonal influence (transplacental hormones)
- Genetic predisposition (may be more common with family history of atopy)
Modifiable:
| Risk Factor | Association |
|---|---|
| Infrequent washing | Not proven causative |
| Overheating | Anecdotal; may worsen symptoms |
Note: There are no strong modifiable risk factors — this is primarily a developmental condition.
Mechanism
Step 1: Maternal Hormonal Influence
- Transplacental passage of maternal androgens in third trimester
- Stimulates infant sebaceous glands to produce excess sebum
- This explains onset in first weeks of life and resolution as maternal hormones wane
Step 2: Sebaceous Gland Overactivity
- Sebum production peaks in early infancy
- Sebaceous glands are most dense on scalp, face, and intertriginous areas
- This explains distribution of disease to these sites
Step 3: Malassezia Yeast Colonisation
- Malassezia species (commensal lipophilic yeasts) proliferate in sebum-rich environment
- Yeast lipases break down sebum triglycerides into free fatty acids
- Free fatty acids are irritant and pro-inflammatory
Step 4: Inflammatory Response
- Mild inflammatory response to yeast products
- Results in erythema, scaling, and greasy crust formation
- Unlike atopic eczema, itch mediators are not significantly activated
Classification
| Subtype | Distribution | Notes |
|---|---|---|
| Localised (cradle cap) | Scalp only | Most common; mildest form |
| Generalised | Scalp + face + nappy area + flexures | Less common; may overlap with psoriasis |
| Leiner disease | Generalised exfoliative erythroderma + diarrhoea + FTT | Rare; associated with complement C3/C5 deficiency |
Differential Diagnosis Considerations
| Condition | Key Differentiating Features |
|---|---|
| Atopic eczema | Itchy; dry rather than greasy; typically onset after 3 months |
| Psoriasis | Well-demarcated thick silvery plaques; may have family history |
| Tinea capitis | Hair loss, broken hairs, lymphadenopathy |
| Langerhans cell histiocytosis | Persistent; petechiae, hepatosplenomegaly |
Symptoms
Typical Presentation:
Associated Features:
Atypical Presentations:
Signs
Scalp:
Face (if involved):
Nappy Area (if involved):
Red Flags
[!CAUTION] Red Flags — Refer urgently if:
- Widespread erythroderma (greater than 90% body surface)
- Signs of secondary infection (weeping, pustules, fever)
- Failure to thrive or diarrhoea (Leiner disease; immunodeficiency)
- Hair loss with broken hairs (fungal infection)
- Persistence beyond 12 months despite treatment
- Recurrent severe infections (immunodeficiency workup)
Structured Approach
General:
- Well-appearing infant (cradle cap does not cause systemic illness)
- Normal growth (plot on centile chart)
- Check for lymphadenopathy (would suggest alternative diagnosis)
Skin Examination:
- Scalp: Distribution, colour (yellow vs pink), texture (greasy vs dry), adherence of scales
- Face: Eyebrows, nasolabial folds, behind ears
- Body folds: Axillae, neck, groins
- Nappy area: Well-demarcated vs diffuse; spares creases?
Hair:
- No hair loss in cradle cap (presence of hair loss suggests tinea capitis)
Special Tests
| Test | Technique | Positive Finding | Clinical Significance |
|---|---|---|---|
| Scale removal | Gentle brushing after oil softening | Scales lift easily without bleeding | Cradle cap; psoriasis scales bleed (Auspitz sign) |
| Wood's lamp | Examine scalp under UV light | Fluorescence (blue-green) | Suggests tinea capitis (Microsporum) |
| Fungal scraping | Scalp scraping for microscopy/culture | Hyphae/spores | Tinea capitis |
First-Line (Bedside)
- Clinical diagnosis — No investigations required in typical cases
- Observation — Monitor response to simple treatment
Laboratory Tests
| Test | Expected Finding | Indication |
|---|---|---|
| None required | N/A | Typical uncomplicated cradle cap |
| Skin swab | Bacterial culture | If secondary infection suspected |
| Fungal scraping/culture | Hyphae/dermatophyte | If tinea capitis suspected (hair loss) |
| Complement levels (C3, C5) | Low | Leiner disease (erythroderma + diarrhoea + FTT) |
| HIV testing | N/A | Severe or recurrent cases; immunodeficiency suspected |
Imaging
Not required for cradle cap.
Diagnostic Criteria
Clinical Diagnosis (No formal criteria — pattern recognition):
- Greasy, yellowish scales on scalp
- Onset in first 3 months of life
- Non-pruritic (not scratching)
- Baby otherwise well
- Resolves by 6-12 months
Management Algorithm
Conservative Management (First-Line)
Reassurance:
- Explain benign, self-limiting nature
- No scarring, no effect on hair growth
- Cosmetic concern only; baby is not in discomfort
Emollient Softening and Scale Removal:
- Apply emollient (olive oil, coconut oil, or commercial baby oil) to scalp
- Leave for 15-60 minutes (or overnight in thick cases)
- Gently brush or comb out loosened scales with soft baby brush
- Wash hair with mild baby shampoo
- Repeat 2-3 times per week until clear
Medical Management
| Treatment | Dose/Application | Indication |
|---|---|---|
| Emollient/oil | Apply then brush out | All cases — first-line |
| Baby shampoo | Regular use | Maintenance |
| Ketoconazole 2% shampoo | 2x per week, leave 5-10 min, rinse | Persistent or inflamed cases |
| Hydrocortisone 1% cream | Apply BD for 1-2 weeks max | Inflamed patches (face, nappy) |
| Clotrimazole 1% cream | Apply BD | If candida superinfection (nappy) |
Key Points:
- Avoid picking scales (can cause bleeding/infection)
- Oil should be washed out — leaving on scalp may worsen condition
- Topical steroids only for short courses; avoid potent steroids on face
Indications for Referral
- Persistence beyond 12 months despite appropriate treatment
- Widespread erythroderma
- Suspected immunodeficiency (recurrent infections, FTT)
- Diagnostic uncertainty (e.g., psoriasis, LCH)
Disposition
- Primary care management: All typical cases
- Dermatology referral: Persistent, widespread, or atypical cases
- Paediatrics referral: Signs of systemic illness, FTT, immunodeficiency
- Follow-up: Only if not resolving with simple measures (4-6 weeks)
Immediate (Rare)
| Complication | Incidence | Presentation | Management |
|---|---|---|---|
| Secondary bacterial infection | 5-10% if scales picked | Weeping, crusting, pustules | Topical/oral antibiotics |
Early (Days-Weeks)
- Cosmetic concern: Parental anxiety about appearance
- Bleeding from scalp: If scales picked or brushed too vigorously
- Candida superinfection: In nappy area; satellite lesions, creases involved
Late (Weeks-Months)
- Persistence: Rare; most resolve by 12 months
- Recurrence in adulthood: Seborrhoeic dermatitis may recur in adolescence/adulthood (different condition but same spectrum)
- Misdiagnosis anxiety: Parents may fear "eczema" or other chronic conditions
Natural History
- Onset typically 2-8 weeks
- Peak at 3-4 months
- Spontaneous resolution by 6-12 months in 90%+
- No long-term sequelae; no scarring; no permanent hair loss
Outcomes with Treatment
| Variable | Outcome |
|---|---|
| Simple emollient/brushing | Clears most cases within weeks |
| Recurrence | May recur until natural resolution age |
| Scarring | None |
| Hair loss | None (if hair loss present, different diagnosis) |
| Development of atopic eczema | No clear link |
Prognostic Factors
Good Prognosis (Virtually All Cases):
- Typical clinical presentation
- Onset before 3 months
- Response to simple measures
- Baby otherwise well and thriving
Consider Alternative Diagnosis If:
- Persists beyond 12 months
- Itchy/baby distressed
- Associated systemic features
- Hair loss present
Key Guidelines
- NICE CKS (Clinical Knowledge Summaries) — Seborrhoeic dermatitis. Pragmatic primary care guidance. NICE CKS
- British Association of Dermatologists Patient Information — Cradle cap information for parents. BAD
- AAP (American Academy of Pediatrics) — Infant skin care recommendations. AAP
Landmark Evidence
Foley et al. (2003) — Natural history of infantile seborrhoeic dermatitis
- Observational study of 1000+ infants
- Key finding: Peak prevalence 3 months; 90% resolved by 12 months
- Clinical Impact: Confirmed self-limiting nature; basis for reassurance
Gupta et al. (2004) — Malassezia and seborrhoeic dermatitis
- Review of pathophysiology
- Key finding: Malassezia colonisation correlates with seborrhoeic dermatitis; antifungals effective
- Clinical Impact: Supports use of ketoconazole shampoo in refractory cases
Evidence Strength
| Intervention | Level | Key Evidence |
|---|---|---|
| Emollient and gentle brushing | 4 | Expert consensus; widespread practice |
| Ketoconazole shampoo | 2b | Observational studies |
| Reassurance/watchful waiting | 4 | Natural history studies |
What is Cradle Cap?
Cradle cap is a very common skin condition in babies that causes thick, yellowish, greasy-looking scales on the scalp. It might look quite dramatic, but it is completely harmless and does not bother your baby at all (it is not itchy or painful). It is caused by overactive oil glands in your baby's skin, which happens because of hormones passed from you during pregnancy.
Is it serious?
No. Cradle cap is not a sign of poor hygiene or any illness. It does not cause any discomfort to your baby and will not cause hair loss or scarring. Most babies grow out of it completely by the time they are 6-12 months old.
How is it treated?
- Do nothing: In most cases, you do not need to do anything — it will go away on its own.
- Oil and brush: If you want to remove the scales for cosmetic reasons, massage a little olive oil, coconut oil, or baby oil into the scalp and leave it for 15-60 minutes (or overnight). Then gently brush the scales off with a soft baby brush and wash the hair with baby shampoo.
- Medicated shampoo: If the cradle cap is very thick or persistent, your doctor may recommend a gentle antifungal shampoo (like ketoconazole) to use twice a week.
What to expect
- The scales may return after you remove them — this is normal
- It usually clears up completely by 6-12 months
- Your baby's hair will grow normally through the scales
When to seek help
See your GP if:
- The rash is spreading beyond the scalp to cover a large area of the body
- The skin looks infected (red, weeping, crusty, or has pus)
- Your baby seems unwell or is not gaining weight
- The condition has not improved by 12 months of age
Primary Guidelines
- NICE Clinical Knowledge Summaries. Seborrhoeic dermatitis. 2023. NICE CKS
- British Association of Dermatologists. Cradle cap (infantile seborrhoeic dermatitis) patient information leaflet. 2023. BAD
Key Literature
- Foley P, et al. The frequency of common skin conditions in preschool-aged children in Australia: seborrheic dermatitis and pityriasis capitis (cradle cap). Arch Dermatol. 2003;139(3):318-322. PMID: 12622624
- Gupta AK, Bluhm R. Seborrheic dermatitis. J Eur Acad Dermatol Venereol. 2004;18(1):13-26. PMID: 14678527
- Elish D, et al. Seborrheic dermatitis: a comprehensive review and update. Actas Dermosifiliogr. 2003;94(7):451-466.
Further Resources
- NHS Cradle Cap: nhs.uk/conditions/cradle-cap
- DermNet NZ: dermnetnz.org/topics/seborrhoeic-dermatitis-of-infants
- Healthychildren.org (AAP): healthychildren.org
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. If you are concerned about your baby's skin, please consult a healthcare professional.