What is Allergic Contact Dermatitis?

Medically Reviewed By Marc Meth, MD, FACAAI, FAAAI
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Allergic contact dermatitis is an itchy, sometimes blistering rash resulting from allergens touching your skin. Allergic contact dermatitis most often appears on your face and hands but can emerge anywhere. Some common contact allergens include nickel, preservatives, essential oils, and some medications. Some occupations also have a higher risk of developing this rash. 

This article explains allergic contact dermatitis in more detail, including its symptoms, causes, and treatment.

What is allergic contact dermatitis? 

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A rash is an area of your skin that becomes irritated. Allergic contact dermatitis is a type of skin rash that appears after you have touched an allergen. You may notice itching alongside a discolored, blistered area. 

An allergen is any substance that causes an allergic reaction. The allergen causes an immune response, as your body senses a threat and produces an inflammatory reaction to protect itself. This reaction causes the rash. A substance that causes an allergic reaction in one person may not cause a rash in another. Specific allergens that induce what is known as type 4 hypersensitivity reactions trigger allergic contact dermatitis.

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Who gets it?

According to recent research, allergic contact dermatitis is common, affecting millions of Americans yearly.

You may be prone to an allergic reaction if you have other skin conditions, such as leg ulcers or atopic dermatitis. When your skin is already compromised, it may be more difficult to cope with allergen exposure.

Read more about allergic reactions.

What are the symptoms of allergic contact dermatitis?

Allergic contact dermatitis is a localized reaction that appears in the area where the allergen made contact with your skin. It may emerge on your face, hands, or any other part of your body. 

If you develop allergic contact dermatitis, you may notice the following symptoms:

  • itching, stinging, or burning
  • blistering
  • swelling in one area of your skin
  • oozing bumps that may crust over after
  • cracking, dry skin

These symptoms may come and go when you have exposure to an allergen.

When should you contact a doctor?

You should consult a doctor if you notice symptoms such as itching, stinging, swelling, or oozing bumps. Your doctor can help develop a treatment plan and provide testing to identify the potential allergen.

You should also contact your doctor if you notice any signs of infection. If your blisters become foul-smelling or have greenish-yellow drainage, there could be an infection.

If you notice any chills or fever, you may require treatment to resolve the infection. 

What can cause allergic contact dermatitis?

Your allergens are unique to you. What causes an allergic reaction in one person may not cause a rash in another. 

There are over 15,000 potential contact allergens, but here are the most common ones:

  • nickel in jewelry
  • fragrances in perfumes and cosmetics
  • balsam of Peru in cosmetics and certain foods
  • latex or rubber in medical supplies
  • urushiol, the allergen in poison ivy, sumac, and oak
  • p-phenylenediamine in hair dye and henna tattoos
  • preservatives in medications and cosmetics
  • medications, such as corticosteroids and some antibiotics
  • chromates in leather and cement

Your doctor may provide you with testing to confirm which allergens may cause your hypersensitivity reaction

Allergic contact dermatitis vs. irritant contact dermatitis

The two main types of contact dermatitis are irritant and allergic. According to current research, 80% of all contact dermatitis cases are irritants. 

Allergic contact dermatitis is a broad immune response to a specific allergen. Your body is overly sensitive to a particular substance and starts an inflammatory response to protect itself from a perceived threat. There may be a delay in the reaction, appearing up to 72 hours after your last exposure. 

Irritant contact dermatitis is a different type of inflammatory response that appears more quickly. For this type of rash, an irritant comes into contact with your skin and damages the area directly. Some common irritants include fruit juice, disinfectants, pesticides, and detergents. 

Read more about irritant contact dermatitis.

How do you diagnose allergic contact dermatitis?

Your doctor can diagnose allergic contact dermatitis during a routine office visit. They may ask you for information such as:

  • when the appearance of the rash occurred
  • your occupation
  • if you can remember coming into contact with any allergens

Your doctor will assess your rash to determine if it is contact dermatitis. Based on the assessment, your doctor may advise further testing to find out if the cause of your rash is due to an irritant or an allergen. 

Testing for irritants 

A doctor may recommend a repeated open application test to determine if your reaction is due to an irritant.

During this test, you will apply a suspected irritant to your skin twice a day for 7 days. If you develop a localized rash, you may be susceptible to that substance. 

Testing for allergens

Your doctor may advise patch testing to determine any potential allergens. During this test, your doctor will apply potential allergens in small amounts and cover the area with a patch.

You will leave the patches on your skin for 48 hours and return to the doctor to see if any of these potential allergens caused a rash. 

How do you treat allergic contact dermatitis?

Your doctor may recommend moisturizing creams, known as emollients, to treat your rash. They may also prescribe a topical corticosteroid to help reduce any swelling. 

In more severe cases, your doctor may advise steroid tablets alongside creams. 

What are the risk factors for allergic contact dermatitis?

The following is a list of occupations that may be more likely to cause allergic contact dermatitis:

  • healthcare workers
  • hairdressers
  • construction workers
  • agricultural workers
  • mechanics and machinists 
  • florists
  • cleaners
  • dental workers
  • food service employees

If you work in these industries, there are ways to minimize the risk of developing allergic contact dermatitis. 

How can you prevent allergic contact dermatitis?

You can prevent allergic contact dermatitis by minimizing your contact with allergens. You can wear personal protective equipment, such as gloves and a gown, to provide a barrier between you and your allergen.

Sometimes, barrier creams can reduce your chances of developing a rash by providing your skin with an additional protective layer. 

What are the complications of allergic contact dermatitis?

You may develop an infection if you scratch the area. Your rash could also spread to different body parts, causing a systemic reaction.

You should receive prompt medical attention to reduce your chances of any complications. 

Summary

Allergic contact dermatitis is a rash that appears up to 72 hours after you come into contact with an allergen. Your immune system perceives allergens as a threat. As a result, your body produces an itchy, blistering rash on the area that came into contact with the allergen.

Some common allergens include nickel, latex, and fragrances. If you are a healthcare worker, hairdresser, or machinist, you may have a higher risk of developing this rash due to repeated exposure to allergens.

If your doctor suspects allergic contact dermatitis, they may recommend a patch test to identify the cause of your rash. You may be able to prevent a future reaction by protecting your skin from being exposed to the allergen. If you seek treatment for your rash, your doctor may advise medicated creams or steroid tablets to help resolve your rash. 

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Medical Reviewer: Marc Meth, MD, FACAAI, FAAAI
Last Review Date: 2022 Oct 31
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