difference between allergic contact dermatitis and irritant contact dermatitis
Allergic contact dermatitis The symptoms of allergic contact dermatitis are very similar to the ones caused by irritant contact dermatitis, which makes the first even harder to diagnose. The first sign of allergic contact dermatitis is the presence of the rash or skin lesion at the site of exposure.[2] Depending on the type of allergen causing it, the rash can ooze, drain or crust and it can become raw, scaled or thickened. Also, it is possible that the skin lesion does not take the form of a rash but it may include papules, blisters, vesicles or even a simple red area. The main difference between the rash caused by allergic contact dermatitis and the one caused by irritant contact dermatitis is that the latter tends to be confined to the area where the trigger touched the skin, whereas in allergic contact dermatitis the rash is more likely to be more widespread on the skin.[3] Another characteristic of the allergic contact dermatitis rash is that it usually appears after a day or two after exposure to the allergen, unlike irritant contact dermatitis that appears immediately after the contact with the trigger.
Food allergy Common foods involved include cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy, wheat, rice, and fruit.[1][2][4] The common allergies vary depending on the country.[1] Risk factors include a family history of allergies, vitamin D deficiency, obesity, and high levels of cleanliness.[1][2] Allergies occur when immunoglobulin E (IgE), part of the body's immune system, binds to food molecules.[1] A protein in the food is usually the problem.[2] This triggers the release of inflammatory chemicals such as histamine.[1] Diagnosis is usually based on a medical history, elimination diet, skin prick test, blood tests for food-specific IgE antibodies, or oral food challenge.[1][2]