What investigations are recommended for a patient with dermatitis that is not responding to first-line treatments?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 14 August 2025Updated: 14 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

For a patient with dermatitis that is not responding to first-line treatments, the following investigations and referrals are recommended:

  • Patch Testing: Patch testing should be offered to people with chronic or persistent dermatitis, particularly hand and facial dermatitis, as clinical features alone are unreliable in distinguishing allergic, irritant, and endogenous dermatitis . It is also recommended for previously well-controlled atopic/endogenous dermatitis that has become difficult or impossible to control with the same topical treatments . Identifying the specific allergen through patch testing can increase adherence and improve outcomes .
  • Referral to Dermatology:
    • Referral to dermatology is recommended if contact dermatitis may be due to topical treatments such as neomycin or corticosteroids .
    • Consider referral to dermatology if dermatitis, especially hand and facial dermatitis, is severe, chronic, recurrent, or persistent .
    • Refer if previously stable dermatitis has become difficult or impossible to control with standard treatments .
    • Refer if allergy to prescribed or over-the-counter topical treatments is suspected .
    • Refer if suspected contact dermatitis does not respond to treatment in primary care, has atypical features, or the diagnosis is unclear .
    • For atopic eczema, refer for a routine dermatology appointment if current management has not controlled the eczema satisfactorily (e.g., one to two flares per month), or if the person is reacting adversely to many emollients .
    • Refer if facial eczema has not responded to appropriate treatment .
    • Refer urgently (within 2 weeks) to dermatology if eczema is severe and has not responded to optimum topical treatment after 1 week ,.
    • Refer if contact allergic dermatitis is suspected, for example, if there is persistent eczema or facial, eyelid, or hand eczema ,.
    • Refer if the diagnosis is, or has become, uncertain ,.
    • Refer if there is recurrent secondary infection .
    • Refer if eczema is assessed as causing significant social or psychological problems, such as sleep disturbance ,.
  • Referral for Suspected Food Allergy: Refer to immunology, dermatology, or paediatrics if a food allergy is suspected and the expertise to diagnose and manage food allergy is not available in primary care ,.

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What Investigations Are Recommended for a Patient With Dermatitis That