Doctor's Notes on Contact Dermatitis
Contact dermatitis is a localized rash/irritation of the skin caused by direct contact with the substance to which the patient’s immune system reacts (allergic type) or by a skin irritant (irritant type). However, signs and symptoms can appear to be visually identical. Signs and symptoms of allergic contact dermatitis usually is a red rash that does not appear for one or two days on the skin after exposure (direct contact with the compound) while irritant type occurs more rapidly. The longer time of exposure to the compound, the more severe the skin reaction. The skin may itch and burn; contact dermatitis usually has more pain than other types of dermatitis and contact dermatitis frequently involves the hands.
Contact dermatitis (allergic type) is caused by a cellular immune response to small, simple molecules (for example, nickel metal in rings or watch bands). Immune cells produce chemicals that cause itches. Plants such as poison ivy, poison oak and poison sumac contain an oil or latex that triggers the dermatitis. Other compounds can include medicines applied to the skin and various cosmetic chemicals.
Contact dermatitis (irritant type) is caused by skin coming in contact with reception that is toxic to your skin. This is not an allergic reaction, it is a toxic reaction. Many chemicals can cause contact dermatitis; frequently encountered chemicals are those in household cleaners like detergents and industrial products such as solvents (for example, turpentine, xylene).
Contact Dermatitis Symptoms
Distinguishing allergic contact dermatitis from irritant contact dermatitis and other forms of dermatitis can be challenging. A full history and physical examination are frequently necessary.
- A red rash is the usual reaction. It appears immediately in irritant contact dermatitis, but in allergic contact dermatitis, the rash does not appear for one to two days after the exposure.
- Your skin may develop small fluid filled structures (vesicles) that can cause weeping, a characteristic of these sorts of eruptions. This condition is distinguished from hives (urticaria) that produce short-lived itchy welts (wheals).
- Hives are most often induced by allergic reactions to orally ingested foods and drugs, but topical contact hives occurs and is mediated by antibodies.
- Your skin will itch and perhaps burn. Irritant contact dermatitis can be more painful than itchy.
- Irritant contact dermatitis often affects the hands, which have been exposed by resting in or dipping into a container (sink, pail, tub) containing the irritant.
- Once a reaction starts, it may take as long as four weeks to resolve completely.
Contact Dermatitis Causes
There are two types of contact dermatitis: allergic and irritant. They often can appear to be visually identical.
- Allergic contact dermatitis often results from an immune response to a small, structurally simple molecule.
- In order to become allergic to such a substance, one must have had at least one previous exposure that eventually induces an immune response.
- This dermatitis is not caused by an antibody but is due to a cellular immune response mediated by a type of blood cell (T-lymphocytes) that has surface molecules that enable it to recognize specific chemical allergens.
- When these lymphocytes come in contact with the allergen, they release a variety chemicals that are able to produce an itchy dermatitis.
- Typically, this sort of reaction occurs only on the skin and requires at least 24 to 48 hours to develop.
- Common plants that produce allergic contact dermatitis include poison ivy, poison oak, and poison sumac. The allergenic chemical is present in the oil or latex that covers stems or leaves.
- Many other substances can cause allergic reactions, including components of hair dyes or straighteners; metallic nickel in jewelry and belt buckles; leather tanning agents; and chemical additives to latex rubber.
- The fragrances in soaps and preservatives and emulsifiers in shampoos, lotions, perfumes, and cosmetics can cause reactions.
- Medications applied to the skin, like neomycin (Neosporin, Neo-Fradin, Neo-Tab), are a common cause of this type of dermatitis.
- Irritant contact dermatitis results from coming in contact with a substance that is directly toxic to your skin. No allergy is required, and it will occur on the first exposure.
- The longer the substance remains on the skin, the more severe the reaction.
- Many chemicals, including industrial cleaning products and solvents, can cause this condition.
- Household cleaners such as detergents can also cause dermatitis.
- People with other skin conditions, such as eczema (atopic dermatitis), are more likely to develop contact dermatitis.
Finding a bump, rash, red mark, or welt on a child's body is more common than not finding one. Most of these are not worrisome; however, some may be more concerning than others. We will present some information about common skin findings in this slide presentation to help patient's better identify them. As always, if there is any concern, always consult the child's doctor to be sure.
Atopic Eczema (Atopic Dermatitis) : Test Your Skin Disorders IQ QuizQuestion
Eczema (also atopic eczema or atopic dermatitis) is a general medical term for many types of skin inflammation.See Answer
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.