Contact Dermatitis: Causes, Symptoms, and Diagnosis

What is contact dermatitis?

Contact dermatitis is an inflammatory reaction of the skin to a substance it comes into contact with externally. There are two main types: irritant contact dermatitis, which occurs when a substance directly disrupts the skin barrier; and allergic contact dermatitis, which occurs when the immune system develops a delayed-type hypersensitivity reaction to a specific substance.

What is irritant contact dermatitis?

Irritant contact dermatitis is the most common type of contact dermatitis. Factors such as water, detergents, soaps, disinfectants, solvents, cleaning agents, and repetitive friction can disrupt the skin barrier.

What is allergic contact dermatitis?

Allergic contact dermatitis develops as a result of the immune system becoming sensitized to a specific substance. This reaction occurs via a Type IV delayed-type hypersensitivity mechanism. Common allergens may include nickel, fragrances, preservatives, hair dyes, rubber chemicals, some topical medications, and cosmetic product ingredients.

What are the symptoms of contact dermatitis?

Redness

Itching

Swelling

Small bubbles

Irrigation

Combustion

In chronic cases, dryness, scaling, cracks, and skin thickening occur.

Where is contact dermatitis most commonly seen?

Location can provide clues to understanding the possible cause. Hands, the area around the ears, eyelids, neck, feet, and scalp/face are commonly affected areas.

How is contact dermatitis diagnosed?

A detailed contact history is important for diagnosis. Cosmetic products, personal care products, cleaning agents, medications, jewelry, workplace chemicals, gloves, and hair dyes may be inquired about.

What is a patch test?

The primary diagnostic method used in patients suspected of having allergic contact dermatitis is the patch test. Standardized allergens are typically applied to the back and evaluated after specific periods of time.

Are patch testing and prick testing the same thing?

No. Patch tests evaluate Type IV delayed-type hypersensitivity. Prick tests, on the other hand, are more commonly used to evaluate immediate allergic reactions mediated by Immunoglobulin E (IgE).

Who can have a patch test?

Recurrent or chronic eczema

Hand eczema

Rashes that may be associated with cosmetic products

occupational dermatitis

Eczema that recurs after certain contacts.

Unexplained resistant dermatitis

How is contact dermatitis treated?

The primary goal of treatment is to identify the responsible irritant or allergen and avoid contact with it as much as possible. Moisturizers, appropriate topical corticosteroids, topical calcineurin inhibitors in some areas, and protective measures may be used.

What is occupational contact dermatitis?

Dermatitis that occurs as a result of repeated contact with water, detergents, chemicals, metals, gloves, or other substances during work can be considered occupational contact dermatitis.

Is contact dermatitis contagious?

No. Contact dermatitis is not an infection and is not contagious.

When should you consult a dermatologist?

If the rash recurs

If it continues for weeks

If the cause cannot be determined

If it seems related to work life

If it recurs repeatedly in areas such as the hands, face, or eyelids

If it doesn't improve despite treatment

If an assessment is needed to determine whether patch testing is necessary

Frequently Asked Questions

Is contact dermatitis an allergy? Not always. Irritant contact dermatitis occurs directly due to damage to the skin barrier.

Can patch tests detect food allergies? No. Their primary use is for delayed-type contact allergies.

If I've been using a product for years, could I develop an allergy to it later? Yes.

Is using cream alone sufficient for contact dermatitis? Not always; identifying the causative agent and avoiding contact is important.

Dermatologist's Note

In contact dermatitis, one of the most important questions is not just "Is there eczema?", but "What is the skin in contact with?". Especially in recurrent cases of hand, facial, eyelid, or occupational dermatitis, a detailed contact history and, in suitable patients, patch testing can significantly alter the course of treatment.