Diagnosis of Contact Dermatitis
Diagnosis of contact dermatitis begins with a detailed medical history and physical examination. Because contact dermatitis can mimic other skin conditions, such as eczema or psoriasis, accurate analysis is essential for effective treatment. Identifying the specific trigger is the key to managing and preventing future flare-ups.
History and Clinical Assessment
Your healthcare provider will ask about:
Recent exposures to chemicals, cosmetics, plants, or metals
Work and hobby-related risks
Use of soaps, detergents, and skincare products
Onset, duration, and pattern of symptoms
Whether the condition improves or worsens with time or certain environments
The location and shape of the rash can offer clues. For example, a reaction around the wrist may indicate an allergy to a watch strap, while widespread hand dermatitis may suggest an irritant like soap or detergent.
Physical Examination | Diagnosis of Contact Dermatitis
The clinician will inspect the skin for signs such as:
Erythema (redness)
Scaling or dryness
Blisters or crusting
Sharp boundaries or geometric shapes that suggest external contact
Patch Testing
Doctors use patch testing as the gold standard when they suspect allergic contact dermatitis. Doctors apply small amounts of common allergens to the skin on the back using adhesive patches. Patches stay on for 48 hours, and doctors monitor the skin for delayed reactions over the following days.
Patch testing can help confirm allergies to:
Metals (nickel, cobalt)
Preservatives (formaldehyde, parabens)
Fragrances
Rubber and latex
Hair dyes (PPD)
This test does not diagnose irritant contact dermatitis, which is usually diagnosed based on history and exclusion of allergy.
Additional Tests | Diagnosis of Contact Dermatitis
If an infection is suspected, a skin swab may be taken to identify bacterial involvement. In rare or difficult cases, a skin biopsy may help rule out other conditions like psoriasis or fungal infections.
To summarise, diagnosis of contact dermatitis relies on a detailed history, visual inspection, and testing when necessary. Accurate identification of triggers enables targeted treatment and long-term prevention.
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