Contact dermatitis can be divided into two groups: Irritative dermatitis and allergic dermatitis.
Irritative dermatitis is caused by irritants in the patient’s environment. Repetitive exposure will eventually exceed the regeneration ability. These irritants can be water, soap, oils, alcohol etc. This causes certain professions to be of a high risk: hair dressers, care workers, cleaners etc., and people with a history of atopic dermatitis are especially at risk.
Allergic dermatitis can basically be caused by anything that the patient develops an allergy towards; most frequently the cause is nickel, perfume or additives. However, finding the culprit can be like finding a needle in a haystack. The methods available are epikutan testing or bullet testing.
Epikutan test works by placing samples of different suspects on the patient’s back. The dermatologist will have a standard sample assembly, but anything the patient works with, his/her perfume, soap, crèmes – anything basically – can be tested at the same time. All the samples are covered with patches and after two days the results are studied. If the patient develops eczema under a specific patch, that test is considered positive.
In a bullet test samples of a couple of suspected causes are tested by placing a drop of a solution and allowing it to enter the skin by pricking a hole in the skin with a needle. This can be used for allergens such as latex, protein, fresh foods or pollen. The allergen will cause a histamine triggered response causing eczema. In order to decipher the result correctly and avoid false positive/negative results, two control drops is used: one with normal saline to rule out contact urticaria and one with histamine to rule out an inability to respond to histamine.
Treatment of either irritative or allergic dermatitis involves avoiding the triggering factor. This can be extremely difficult and require months of experimenting with different causes not to mention eventually requiring a change of jobs.
Medical treatment includes focally applied steroids (in severe cases systemic steroids can be tried), disinfecting ‘red baths’, anti-inflammatory medicine, ultraviolet light and antibiotics in case of secondary infection.