Сause of contact dermatitis.

Dermatitis is a broad term covering many different disorders that all result in a red, itchy rash. The term eczema is sometimes used for dermatitis. Some types of dermatitis affect only specific parts of the body, whereas others can occur anywhere. Some types of dermatitis have a known cause, whereas others do not. However, dermatitis is always the skin's way of reacting to severe dryness, scratching, an irritating substance, or an allergen. Typically, that substance comes in direct contact with the skin, but sometimes the substance is swallowed.
Contact Dermatitis is an inflammation (reddening) of the skin. It is caused by contact with a substance such as soap or chemicals. The dermatitis may ... be caused by contact with plants, such as poison ivy, poison oak, and ragweed.
This type of Dermatitis occurs with an allergen such as poison ivy or an irritant such as skin soap. Signs and symptoms include redness and itching. In severe cases, you may have blisters and weeping sores. The skin changes in contact Dermatitis are limited to where you had contact with the allergen or irritant.
Should you develop a contact dermatitis, see your dermatologist for relief. He/she can perform a patch test to determine the irritating substance. If you suspect a nickel allergy, it is a good idea to have the dermatologist test for nickel sensitivity when considering having ears pierced. In any case, the piercing should be done with a stainless-steel needle. As a further precaution, stainless-steel or high-quality 18 karat gold studs should be worn as the first pair of earrings. Nickel sensitivity often does not result in a rash for weeks or months after contact with the metal.