Contact dermatitis is a skin disease characterized by red, itchy rash due to contact with an allergen or irritant. The skin reaction is usually observed a couple of hours to a few days after the skin contact. The resulting rash is not contagious and rarely life-threatening. It can progress to swelling, severe redness and large blisters.
Types of contact dermatitis:
- Allergic contact dermatitis is due to the immune reaction of the body when an allergen comes in contact with the skin. Inflammatory chemicals cause the itchiness and irritation of the skin. The allergen can cause a systemic effect if it enters the body. Common allergens include nickel, drugs in skin creams, formaldehyde, cosmetic and skincare products, latex gloves, skin tattoo, plants, airborne substances and products that cause reaction when exposed to the sun.
- Irritant contact dermatitis is a non-allergic inflammatory reaction that occurs when an irritant directly damages the outer protective layer of the skin. This can result after a single or repeated exposure. Common irritants include acids, alkalis, solvents like acetone and rubbing alcohol, strong soaps, plants and body fluids like urine and saliva.
- Occupational contact dermatitis results from exposure to irritants or allergens encountered on the job site. Examples of occupations with increased risk to such disease include healthcare workers, metalworkers, construction workers, hairdressers, gardeners and agricultural workers.
Identifying the underlying cause and type of contact dermatitis are important for proper treatment. The patient’s medical history and physical exam helps identify the allergen or irritant that caused the rash. A patch test also known as hypersensitivity allergy test can be done if the cause of rash cannot be easily identified. Small amounts of common allergens are placed on the skin for 2 days. The presence of skin reaction confirms a substance as an allergen for the patient.
Complications of contact dermatitis include infection of the affected area due to repeated scratching and neurodermatitis. Neurodermatitis occurs when a skin that is repeatedly scratched becomes discolored, thick and leathery.
The skin in contact with an allergen presents the following:
Skin redness that can progress to swelling with blisters or ulceration
The skin in contact with an irritant presents the following:
More painful than itchy rashes
Cracking skin due to dryness
Stiff or tightened feeling of skin
Open sores that form crusts
Commonly Prescribed Drugs
- Topical corticosteroids reduce skin inflammation and itchiness. A commonly prescribed drug is mometasone which is in the medium range of potency and for patients of at least 2 years old. The treated skin should not be covered or wrapped in bandage. Side effects: mild burning or stinging sensation, thinning of skin, skin color changes, acne, increased hair growth.
- Oral corticosteroids are prescribed during severe contact dermatitis and when a large area of the skin is affected. Side effects: reduced growth rate in children, hypertension, osteoporosis, diabetes.
- Antihistamines reduce the allergic response and decrease the itchiness of the affected area. A commonly prescribed drug is diphenhydramine. It can cause dizziness and drowsiness so the patient should take caution when performing activities that require alertness.
- Topical emollients moisturize the skin by reducing water loss and forming a protective barrier over it. Ointments are used for very dry skin for its high oil content while creams and lotions work for less dry, but inflamed skin. Emollients can be used as substitutes for soaps, added to bath water or used while in the shower. Do not rub in the emollient. Lightly smooth it out in the direction of hair growth.