Nappy Rash
Summary
Nappy Rash (Diaper Dermatitis) is an umbrella term for skin eruptions in the diaper area. The most common cause is Irritant Contact Dermatitis (Ammonia dermatitis), affecting 25% of infants. The key clinical distinction is between Irritant Dermatitis (which affects convex surfaces and spares the flexures) and Candidal Dermatitis (which involves the deep flexures and presents with satellite lesions). Management involves the "ABCDE" protocol: Air, Barrier, Cleansing, Diaper choice, and Education. [1,2]
Clinical Pearls
The "Flexural Sparing" Sign: Urine and faeces usually do not penetrate deep into the inguinal folds due to skin apposition. Therefore, a rash that SPARES the creases is almost certainly Irritant Dermatitis. A rash that INVOLVES the creases (where fungi thrive in the warmth) is Candida or Seborrheic Dermatitis.
Zinc Deficiency Flag: A severe, erosive nappy rash that resists treatment, especially when associated with perioral dermatitis and alopecia, suggests Acrodermatitis Enteropathica (Zinc deficiency). This is a rare but critical "do not miss".
Langerhans Cell Histiocytosis: A rare mimic. Chronic nappy rash with petechiae/purpura or "cradle cap" that is unresponsive to treatment should prompt biopsy.
Demographics
- Prevalence: 25-50% of infants.
- Peak Incidence: 9-12 months.
- Risk Factors:
- Introduction of solids (changes faecal pH).
- Antibiotic use (diarrhoea + fungal overgrowth).
- Diarrhoea.
Mechanisms of Injury
- Barrier Breakdown: Hyperhydration (wet skin) disrupts the stratum corneum.
- Chemical Irritation:
- Faecal bacteria produce Urease.
- Urease cleaves Urinary Urea -> Ammonia.
- Ammonia raises pH (Alkaline).
- Alkaline pH activates faecal enzymes (Proteases and Lipases) which digest the skin.
- Therefore: Urine + Faeces is much worse than either alone.
- Mechanical: Friction from the nappy.
| Condition | Appearance | Creases | Other Features |
|---|---|---|---|
| Irritant Dermatitis | Glazed, shiny, red. Convex surfaces. | SPARED | Painful. |
| Candidal Infection | Beefy bright red. | INVOLVED | Satellite pustules. Oral thrush. |
| Seborrhoeic Derm | Salmon pink, greasy scale. | INVOLVED | Cradle cap. Axillary rash. |
| Psoriasis | Well defined red plaques. Silver scale. | Touches | Family history. |
| Impetigo | Golden crusts / Bullae. | Variable | Staph aureus. |
Symptoms
Diagnosis
- Clinical: Based on distribution and morphology.
- Microbiology:
- Skin swab for C/S if bacterial superinfection (Impetigo) suspected.
- Candida is often a clinical diagnosis.
- Biopsy: Only if chronic and unresponsive (rule out LCH/Zinc deficiency).
The ABCDE Protocol
NAPPY RASH MANAGEMENT
↓
IS IT CANDIDA? (Creases + Satellites)
┌─────────┴─────────┐
NO (Irritant) YES (Thrush)
↓ ↓
ABCDE PROTOCOL ADD ANTI-FUNGAL
(Standard Care) (Clotrimazole)
↓ ↓
A: AIR (Nappy free time)
B: BARRIER (Sudocrem/Metanium)
- Apply THINLY (translucent)
C: CLEANING (Water + Cotton wool)
- NO WIPES (sting/allergy)
D: DIAPER (High absorbency)
- Change every 2-3 hours
E: EDUCATION
↓
IF SEVERE INFLAMMATION:
- Add 1% Hydrocortisone (max 7 days)
- Apply steroid first, wait, then barrier.
Therapeutics
- Barrier Creams:
- Zinc Oxide (Sudocrem): Antiseptic and barrier.
- Titanium Dioxide (Metanium): Very drying. Good for weeping rashes.
- Key: Apply ONLY thin layers. Thick paste traps moisture and bacteria.
- Anti-Fungals:
- Clotrimazole / Miconazole.
- Daktacort (Miconazole + Hydrocortisone): Excellent for inflamed thrush. Use for 7 days.
- Bacterial Superinfection: Staph aureus (Impetigo) or Strep. Needs Flucloxacillin.
- Granuloma Gluteale Infantum: Purple/Red nodules. Caused by occlusive nappy + potent steroids.
- Scarring: From severe ulceration (Jacquet's).
- Acute: Most resolve within 3 days of "Air and Barrier".
- Chronic: If lasts >4 weeks despite treatment, RE-EVALUATE. Consider Zinc deficiency, Cow's Milk Allergy, or LCH.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Nappy Rash | NICE CKS | Clinical diagnosis. Stepwise care. |
| Skin Care | AWHONN | Guidelines for neonatal skin care. |
Landmark Evidence
1. Atherton (2001)
- Review paper establishing the "Ammonia" hypothesis and the interaction between faecal enzymes and urinary pH.
Why has my baby got this?
It's usually a chemical burn. When pee and poo mix in the nappy, they make Ammonia (like bleach). Because the skin is wet and rubbed by the nappy, this chemical burns the top layer of skin. It is not because of poor hygiene – it happens to almost all babies at some point!
Is it Thrush?
If the rash goes right deep into the skin creases/folds and has little red spots ("satellites") scattered around the edge, it is likely Thrush (a yeast infection). Yeast loves warm, dark, moist places. You will need an anti-fungal cream.
What is the best cure?
Fresh Air. The nappy is like a greenhouse. Lay your baby on a towel without a nappy for 30-60 minutes a day. The air heals the skin faster than any cream.
Barrier Creams
Use them, but use them sparingly. You should be able to see the skin through the cream. If you paste it on thick like icing, it traps the wetness against the skin and makes it worse.
Primary Sources
- Atherton DJ. The aetiology and management of irritant diaper dermatitis. J Eur Acad Dermatol Venereol. 2001.
- Shin HT. Diaper dermatitis that does not quit. Dermatol Ther. 2005.
- NICE CKS. Nappy rash. 2022.
Common Exam Questions
- Diagnosis: "Rash sparing flexures?"
- Answer: Irritant Contact Dermatitis.
- Diagnosis: "Rash involving flexures with satellite pustules?"
- Answer: Candidiasis.
- Safety: "Why avoid Talcum powder?"
- Answer: Inhalation risk (pneumonitis).
- Pathology: "Role of Urease?"
- Answer: Converts Urea to Ammonia (Raising pH).
Viva Points
- Cloth vs Disposable Nappies: Modern disposables contain "Super Absorbent Polymers" (SAP) that wick moisture away instantly. They are clinically proven to be better for preventing nappy rash than cloth nappies (which hold wetness against skin).
- Acrodermatitis Enteropathica: Always mention this as a differential for resistant rash.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.