01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Inspect the entire fold with consent, privacy and a chaperone by preference. Assess symmetry, edge, scale, satellite lesions, fissures, odour, drainage and adjacent genital or perianal skin. Ask about pain, itch, sweating, continence, diabetes symptoms, antibiotics, immunosuppression, new products and previous antifungal or steroid exposure.
Treatment has two equal components: restore a dry low-friction environment and reduce yeast. Pat rather than rub dry, change damp clothing, use breathable fabrics and place a soft absorbent separator where appropriate. Avoid talc inhalation and caking powders in eroded skin. Topical azoles cover Candida and some dermatophytes, but persistent disease needs a diagnosis rather than endless empirical cream.
Do not blame body shape or hygiene. Offer weight or glycaemic support when relevant while treating the current inflammation immediately. Recurrent candidiasis can be an early diabetes clue; unusually extensive refractory infection can signal immune compromise. Conversely, a positive surface yeast result can represent colonisation of inverse psoriasis, so reconcile laboratory findings with morphology and response.
Key points
- Candidal intertrigo is a sore, moist, confluent fold eruption with maceration, fissures and possible satellite papules or pustules.
- Erythema may look red, violet, grey or dark brown across skin tones; gloss, erosion, tenderness and satellite morphology are often more reliable.
- Reduce moisture and friction with gentle drying, breathable clothing, absorbent non-adherent material and management of sweat or incontinence.
- Apply clotrimazole 1% cream thinly two or three times daily for at least two weeks according to the licensed product.
- Avoid potent steroid–antifungal mixtures and prolonged fold steroid exposure; use a brief low-potency anti-inflammatory only for a defined indication.
- Take fungal sampling for recurrent, atypical or treatment-resistant disease and bacterial culture when pus, odour, cellulitis or systemic illness suggests coinfection.
- Check HbA1c when recurrence or symptoms suggest diabetes, but do not order broad immune testing for one ordinary episode.
- Reconsider inverse psoriasis, erythrasma, tinea, contact dermatitis and flexural blistering disease when a correctly applied course fails.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Candida overgrowth
Commensal Candida proliferates where heat, moisture and occlusion disrupt fold barrier, rather than being acquired necessarily from another person.
Mechanical maceration
Skin-on-skin friction, sweat, incontinence and tight clothing soften stratum corneum and create fissures that permit yeast-associated inflammation.
Metabolic and medicine risk
Diabetes, obesity, pregnancy, recent antibiotics, corticosteroids and immune suppression increase recurrence or severity and shape investigation.
Local anatomical factors
Inframammary, abdominal, groin, genital, perianal and interdigital folds retain moisture; appliances and poorly fitting prostheses can create additional sites.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Barrier breakdown
Hydrated keratin loses integrity under friction, producing soreness, fissuring and a glossy eroded surface vulnerable to microbial overgrowth.
- 2Yeast-to-hyphal transition
Candida adheres and forms invasive superficial hyphae in permissive moist skin, stimulating neutrophilic pustules around the main plaque.
- 3Satellite spread
Small papules or pustules arise beyond the confluent fold edge, a useful but not obligatory clue to Candida.
- 4Mixed fold microbiology
Corynebacteria, staphylococci and Gram-negative organisms can coexist, so odour or maceration alone does not establish one pathogen.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
A glossy sore erythematous or hyperpigmented plaque occupies opposing surfaces with maceration at the deepest crease.
Small papules or pustules beyond the main margin strengthen a Candida diagnosis when aligned with the moist fold pattern.
Linear splits at the fold base cause burning with movement and can admit secondary bacteria.
A dry brown-red patch with minimal satellite inflammation and coral-red Wood-lamp fluorescence suggests Corynebacterium.
Rapid spread, disproportionate pain, crepitus, necrosis, fever or shock is not uncomplicated intertrigo and needs emergency care.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Skin scraping or fungal swabFirst step - Why
- Confirm Candida or dermatophyte in recurrent, atypical or non-responsive disease.
- Interpretation and limitations
- Sample an active satellite or edge before more treatment; Candida colonisation must be interpreted with clinical morphology.
- 02
Bacterial culture - Why
- Assess purulence, malodour, cellulitis or treatment failure for bacterial coinfection.
- Interpretation and limitations
- Collect from fresh pus or erosion after gentle cleaning and avoid treating mixed colonisers without invasive features.
- 03
Wood lamp examination - Why
- Support erythrasma when a brown minimally scaly fold plaque is present.
- Interpretation and limitations
- Coral-red fluorescence supports porphyrin-producing Corynebacterium but can be reduced by recent washing or antibiotics.
- 04
HbA1c or glucose - Why
- Detect diabetes when infection recurs or metabolic symptoms and risk are present.
- Interpretation and limitations
- Act on glycaemic results while treating skin; a normal test does not exclude local moisture and friction drivers.
- 05
Biopsy for persistent erosive disease - Why
- Investigate psoriasis, Hailey-Hailey, pemphigus or malignancy when morphology remains atypical.
- Interpretation and limitations
- Choose an active edge and coordinate routine histology or immunofluorescence specimen handling before anaesthetic and fixation.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Inverse psoriasis
Smooth well-demarcated symmetrical plaques, psoriasis elsewhere and nail pitting favour flexural psoriasis, which can coexist with yeast colonisation.
Dermatophyte infection
An advancing scaly border with central clearing and groin scrotal sparing suggests tinea rather than confluent moist candidiasis.
Erythrasma
Brown-red minimally inflamed fold patches with characteristic coral-red Wood-lamp fluorescence support superficial Corynebacterium infection rather than yeast.
Contact dermatitis
Prominent itch, sharp exposure pattern and new wipes, deodorant, dressings or topical products point to irritant or allergic dermatitis.
Hailey-Hailey or pemphigus
Recurrent painful erosions, family history, blisters or lesions beyond folds may require biopsy and direct immunofluorescence.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Typical uncomplicated diseaseDry and treat the foldFirst stepA local moist satellite-pustular fold eruption occurs without invasive infection or major immune compromise.+
- 1Clean gently, pat completely dry, reduce friction and moisture and address incontinence or occlusive clothing.
- 2Apply clotrimazole 1% cream thinly two or three times daily for at least two weeks, extending to the affected margin.
- 3Review tolerance and response, continuing environmental measures after clearance and avoiding unneeded antibiotic or potent steroid combinations.
02Inflamed or recurrentConfirm organism and driversPainful inflammation, repeated episodes or incomplete response persists despite credible use.+
- 1Obtain fungal and bacterial samples from appropriate active lesions and review all topical products, antibiotics, diabetes and immune risk.
- 2Use a brief low-potency corticosteroid separately only when substantial inflammatory dermatitis is diagnosed, continuing adequate antifungal treatment.
- 3Treat confirmed coinfection and metabolic drivers, then reassess morphology for psoriasis, tinea or contact allergy.
03Severe or atypicalEscalate depth and host assessmentEscalationDisease is extensive, eroded, rapidly progressive, systemic or refractory in an immunocompromised patient.+
- 1Assess sepsis, necrotising features and diabetic decompensation and refer urgently when dangerous depth or perineal disease is possible.
- 2Use specialist-guided systemic antifungal treatment only after organism, interactions, pregnancy and liver risk are reviewed.
- 3Arrange dermatology assessment and biopsy for persistent erosions or suspected inflammatory blistering disease.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
Clotrimazole 1% cream
Apply a thin layer two or three times daily to clean dry affected folds for at least two weeks according to response and product information.Avoid eyes and mucosa, stop for marked irritation or allergy, and recognise that some excipients can damage latex contraception or provoke contact dermatitis.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Fissure and bacterial superinfection
Eroded fold skin can develop bacterial cellulitis, malodour and increasing pain, particularly with diabetes, lymphoedema or immune compromise.
Recurrent chronic inflammation
Persistent moisture, friction, incontinence or uncontrolled glycaemia sustains repeated episodes despite otherwise correct short topical antifungal courses.
Post-inflammatory pigment change
Inflammation and irritant powders or combination creams can leave prolonged, distressing hyperpigmentation or hypopigmentation in previously active flexures.
Steroid adverse effects
Potent or prolonged fold corticosteroid is amplified by occlusion and can cause atrophy, striae and masked fungal expansion.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Review soreness, maceration, fissures and satellites after two weeks, distinguishing pigment residue from active moist inflammation.
- Check application continued into the fold rather than being removed immediately by sweat, washing or opposing skin.
- Reassess glucose, continence, clothing and medicine drivers when disease returns quickly.
- Escalate fever, rapid spread, severe pain, necrosis or systemic decline immediately.
- For repeated treatment failure, obtain samples and reconsider psoriasis, erythrasma, tinea and contact allergy before prescribing another cream.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Dryness is pharmacological
Changing the moist frictional environment removes the condition Candida needs and is as important as antifungal cream.
Satellites support not prove
Peripheral pustules are useful, but sampling and response matter when psoriasis or bacterial disease can coexist.
Occlusion amplifies steroid
Flexures absorb corticosteroid strongly, increasing atrophy and striae risk from potent or prolonged treatment.
Yeast may colonise psoriasis
A positive swab cannot by itself explain a sharply demarcated symmetrical chronic flexural plaque.
11Common pitfallsFrequent interpretation and management errors.
- 01
Calling every fold rash Candida and missing inverse psoriasis or erythrasma.
- 02
Prescribing repeated potent steroid–antifungal combination creams in an occluded groin.
- 03
Using a positive surface swab without correlating organism, morphology and response.
- 04
Telling a patient weight loss must occur before current painful disease can be treated.
- 05
Missing necrotising perineal infection because early colour change appears modest on dark skin.