Type 4 allergic contact dermatitis is a form of allergic contact dermatitis that is caused by an allergic reaction to a substance that comes into direct contact with the skin. It is sometimes referred to as delayed-type hypersensitivity or allergic patch test reaction. It is caused by the body's immune system overreacting to a particular substance. The reaction can cause redness, itching, and swelling of the affected area. In some cases, the reaction can be severe and cause blistering and inflammation.
What Causes Type 4 Allergic Contact Dermatitis?
Type 4 allergic contact dermatitis is caused by an allergic reaction to a substance that comes into direct contact with the skin. This type of reaction is often caused by a chemical irritant, such as a preservative, fragrance, or dye. It can also be caused by certain metals, such as nickel, cobalt, and chromium.
What Are the Symptoms of Type 4 Allergic Contact Dermatitis?
The symptoms of type 4 allergic contact dermatitis can vary from person to person. Generally, the affected area will become red, itchy, and swollen. Blistering and inflammation may also occur. In some cases, the affected area may become dry and scaly.
How Is Type 4 Allergic Contact Dermatitis Diagnosed?
The diagnosis of type 4 allergic contact dermatitis is usually made based on the patient's medical history and by performing a physical examination. In some cases, a skin patch test may be performed to determine what substance is causing the reaction.
How Is Type 4 Allergic Contact Dermatitis Treated?
The treatment of type 4 allergic contact dermatitis depends on the severity of the reaction. Generally, the affected area should be kept clean and dry. Over-the-counter antihistamines may be used to reduce itching and inflammation. In more severe cases, a topical steroid cream may be prescribed.
