Contact Dermatitis and Allergic Reactions

What is contact dermatitis?

Contact dermatitis is an inflammatory skin reaction secondary to exposure to a foreign substance.  There are two types of contact dermatitis.  Irritant and allergic dermatitis. contact dermatitisIrritant contact dermatitis is caused by exposure to a harsh substance that causes the skin to be inflamed.  The inflammation is not caused by the body’s immune system.  In contrast allergic contact dermatitis is due to developing a sensitivity to a foreign substance and upon re-exposure the body will react to the substance via the immune system.

What are the symptoms of contact dermatitis?

The symptoms of contact dermatitis are itching, redness, swelling, and dryness.  The area that is affected is typically well demarcated and can be present on various parts of the body.  On the foot some common substances causing a reaction are adhesive tapes, nickel, poison ivy, and perfumes.  The top of the foot is most often affected when exposed to a irritating substance.   

How do you diagnose contact dermatitis?

The doctor will use his/her clinical skills to determine the diagnosis of contact dermatitis.  A thorough medical history will also be taken into account to help find the causative agent.  The doctor may also attain a punch biopsy or skin shaving to confirm the diagnosis.  This diagnostic procedure is virtually painless and can be performed in the office. 

How do you treat contact dermatitis?

Treatment for moderate cases involves the use of topical steroids such as triamcinolone and clobetasol.  The doctor may choose different vehicles for the topical steroid in order to increase effectiveness.  The most potent vehicle is an ointment and the least penetrative is a cream.  For severe cases the doctor may prescribe oral steroids such as methylprednisolone or prednisone.  Typically, removal of the irritant and topical treatment is effective and oral steroids are used infrequently. 

How do I prevent contact dermatitis?

It is difficult to prevent contact dermatitis unless the patient is aware of all the substances the patient is allergic to.  Poison ivy can be identified and therefore be avoided but a patient will not know if a certain substance is an allergen until they come into contact with it a second time.  The first exposure will not cause a reaction unless it is an irritant.  A true allergic reaction requires an initial exposure and a subsequent handling of the substance.

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