What is contact dermatitis?

Contact dermatitis is a reaction that happens after your skin comes in contact with certain substances.

Skin irritants cause most contact dermatitis reactions. Other cases are caused by allergens, which trigger an allergic response. The reaction may not start until 24 to 48 hours after exposure. Contact dermatitis, caused by an irritant that is not an allergic response, happens from direct contact with the irritant.

Allergic contact dermatitis most commonly affects adults, but it can affect people of all ages.

What causes contact dermatitis?

Some of the most common causes of contact dermatitis include:

• Soaps
• Drool
• Different foods
• Detergents
• Harsh baby lotions
• Perfumes
• Rubber (latex)
• Antibiotics
• Fragrances
• Preservatives

Plants, metals, cosmetics, and medicines may also cause a contact dermatitis reaction:

Poison ivy

Poison ivy is part of a plant family that includes poison oak and sumac. It is one of the most common causes of a contact dermatitis reaction.

Metals

Many chemical agents can cause allergic contact dermatitis. Nickel, chrome, and mercury are the most common metals that cause contact dermatitis:

• Nickel is found in costume jewelry, and belt buckles. Watches, zippers, snaps, and hooks on clothing may also contain nickel.
• Chrome-plated items, which contain nickel. These will probably cause skin reactions in people sensitive to nickel.
• Mercury, which is found in contact lens solutions. This can cause a reaction in some people.

Cosmetics

Many types of cosmetics can cause allergic contact dermatitis. Permanent hair dyes that contain paraphenylenediamine are often causes. Other products that may cause problems include dyes used in clothing, perfumes, eye shadow, nail polish, lipstick, and some sunscreens.

Medicines

Neomycin is found in antibiotic creams, such as triple antibiotic ointment. It is a common cause of medicine-related contact dermatitis. Penicillin, sulfa medicines, and local anesthetics, such as procaine hydrochloride or paraben, are other possible causes.

What are the symptoms of contact dermatitis?

The following are the most common symptoms of contact dermatitis. However, each person may experience symptoms differently. Symptoms may include:

• Mild redness and swelling of the skin
• Blistering of the skin
• Itching
• Scaly, thickened skin

The most severe reaction is at the contact site. The symptoms of contact dermatitis may look like other skin conditions. Always talk with your healthcare provider for a diagnosis.

How is contact dermatitis diagnosed?

Diagnosis is usually based on a medical history and physical exam. Patch testing can be done to identify the allergen that is causing the rash. A skin biopsy may also be performed. 

How is contact dermatitis treated?

Specific treatment for contact dermatitis will be determined by your healthcare provider based on:

• Your age, overall health, and medical history
• Extent of the reaction
• Your tolerance for specific medicines, procedures, or therapies
• Expectations for the course of the reaction
• Your opinion or preference

The best treatment is to identify and avoid the substances that may have caused the allergic reaction. The following are common treatment recommendations for mild to moderate reactions:

• Thoroughly wash skin with soap and water as soon after the exposure as possible.
• Wash clothing and all objects that touched plant resins (poison ivy/oak) to prevent re-exposure.
• Use wet, cold compresses to soothe inflammation if blisters are broken.
• Use barrier creams to block certain substances if there is a chance of re-exposure in the future.
• Medicines you put on your skin or ones you take by mouth may be recommended by your healthcare provider to relieve itching.
• Cortisone creams are used topically to relieve itching.
• Oral or injected steroids and oral antihistamines are used to control the itching and rash.
• Avoid scratching the rash to prevent a bacterial infection.
• For severe reactions, always contact your healthcare provider.

If the reaction is significant and the substance that caused it can't be determined, your healthcare provider may do a series of patch tests to help identify the irritant.

Can contact dermatitis be prevented?

The only way to prevent contact dermatitis is to avoid contact with the irritant or allergen that causes it.

Key points about contact dermatitis

• Contact dermatitis is a physiological reaction that happens after skin comes in contact with certain substances.
• Skin irritants cause most contact dermatitis reactions.
• Allergens can cause an allergic reaction that results in contact dermatitis.
• It is important to identify the cause of your contact dermatitis so you can avoid contact with that substance.
• Topical and oral medicines may be recommended by your healthcare provider to relieve itching.

Next steps

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your provider tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your provider if you have questions.