Synopsis
Distinguish delayed contact-allergy patch testing from immediate hypersensitivity skin-prick testing, prepare patients safely, and interpret sensitisation only within a compatible history.
- Patch testing evaluates delayed type IV allergic contact dermatitis by applying allergens under occlusion and reading reactions after defined intervals.
- Skin-prick testing evaluates immediate IgE sensitisation within minutes using positive and negative controls in a setting equipped for systemic reactions.
- A positive result shows sensitisation, not automatically clinical allergy; relevance depends on exposure, timing, distribution and symptoms.
- Antihistamines suppress prick-test wheals but generally do not prevent delayed patch reactions; topical corticosteroid at the test site can suppress either local response.
- For Patch testing and prick testing distinctions, describe what is seen before assigning a diagnosis, and record site, extent, symptoms, duration and change over time.
- A technically adequate result in Patch testing and prick testing distinctions can still be misleading when the wrong lesion, site, preparation or clinical question was selected.
Key red flags
Airway swelling, breathing difficulty, hypotension or rapidly progressive multisystem allergy requires emergency treatment; neither patch nor prick testing belongs in acute resuscitation.
Previous severe immediate reactions require specialist planning and resuscitation readiness before any provocation or skin test.
Investigation priorities
Identify contact sensitisation relevant to chronic eczematous disease.
Management branches
The patient is stable and the result will alter diagnosis, referral or follow-up.
- Define the question for Patch testing and prick testing distinctions, explain the process and obtain valid consent before exposing, touching, photographing or sampling skin.
- Choose representative anatomy, optimise lighting or specimen technique, and document site, morphology, symptoms and relevant previous treatment. Apply that step specifically within the patch testing and prick testing distinctions assessment and its recorded clinical context.
- Interpret the result beside the full clinical pattern, communicate uncertainty and arrange ownership of results and safety-netting. Apply that step specifically within the patch testing and prick testing distinctions assessment and its recorded clinical context.