Allergic Skin Reactions
Allergic skin reactions are due to several causes. The most common cause is contact allergy which means that a chemical touching the skin has caused an allergy. Poison ivy is the classic form of a contact allergic dermatitis. Many other chemicals can also cause skin allergy by touching the skin such as occupational exposure, exposure to chemicals used in hobbies, other plant dermatitis, allergies to topically applied cosmetics or medications, or contact with foods. The inciting chemical may be a known allergen in the case of nickel, or it may be a rare or unknown cause of allergies. These chemicals do not cause allergies in most people who are exposed. Repeated exposure is necessary to develop an allergy; in other words, you may develop an allergy to a product you've used before without problems. Another factor which may be involved in the development of the allergic condition is hypoglycemia, which can trigger other allergic conditions such as hayfever and asthma.
A second cause of allergic skin rashes are ingested drugs, food chemicals, or inhaled chemicals. An instance of the first cause is a rash due to taking penicillin or other medication. Frequently, many food additives such as soy or chemical dyes can also cause allergic rashes. Finally, inhalation of chemicals such as formaldehyde from paint, carpet or furnishings can cause allergic skin rashes.
Treatment always involves the avoidance of the offending chemical but first it must be identified. In order to sort through all these possibilities, consultation with a board-certified dermatologist with experience in skin allergies is key. A specialist will be able to detect clues in the patient's history and exam which will point to either a contact allergy or a systemic allergy and will likely be able to identify the offending product and prescribe the appropriate treatment.
Treatment also includes gentle treatment of the skin. It's of the utmost importance to avoid soaps on the skin rash because the skin is injured, and soaps can further damage this skin. Moisturization and probably a topical anti inflammatory medication will be prescribed to provide relief of itching. With proper treatment, allergic skin rashes usually clear up within 2 weeks provided the offending chemical is avoided.
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