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Allergic contact dermatitis

ivy allergyAllergic contact dermatitis is when your skin comes into contact with something you're allergic to (called an allergen).

It's different to irritant contact dermatitis because while irritant contact dermatitis can affect anyone, you'll only get allergic contact dermatitis if you're allergic to certain things that touch your skin.

Allergic contact dermatitis happens due to an allergic reaction to a chemical or substance that causes your body to have an immune reaction. Many things can cause this, the most common are nickel (in a lot of jewellery), rubber (latex), hair dyes, some plants (such as ivy), and chemicals in make-up, soap, skincare products, and plasters.

Symptoms of allergic contact dermatitis

If you have allergic contact dermatitis, you'll develop an itchy rash after coming into contact with the allergen. For example, you may get a rash on your eyelids if you're allergic to a chemical in your make-up or a rash under your watch strap if you're allergic to nickel.

The rash usually occurs a few hours after the contact, not within a few minutes like with hives. Your skin can become red, sore and swollen. This will settle down after a few days as long as your skin is no longer in contact with the allergen.

Diagnosing allergic contact dermatitis

Your GP can usually diagnose allergic contact dermatitis by the appearance of your skin. They'll ask you questions about your symptoms, including when they first appeared, what you're in contact with and what worsened the symptoms. With your help, your GP will try to identify the allergen.

Laboratory tests are not usually required but if it's not obvious what the allergen is, you might be referred to see a dermatologist (skin doctor) for patch testing. You can read about patch testing on DermNet NZ.

If you think your make-up or skincare products are causing allergic contact dermatitis, you can test them at home with a simple test (called the open user test). Put the product onto a small area of sensitive skin (such as the inside of your upper arm) twice a day for five to 10 days in a row. If you get a rash there, it's likely you have allergic contact dermatitis. This is a useful way to check your products so you can stop using anything that causes problems.

Treating allergic contact dermatitis

Treatment includes:

Getting help for allergic contact dermatitis

See your GP if the rash is severe, affecting a large area, or if it doesn't improve with hydrocortisone cream after a few days. You might need stronger steroid creams or even steroid tablets (prednisone) to heal the redness and itch.

Your GP may refer you to a dermatologist (a specialist skin doctor). If you prefer, you can pay to see a private dermatologist. You can find a dermatologist on:

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Written by HealthInfo clinical advisers. Last reviewed June 2021.

Sources

Page reference: 326086

Review key: HICOD-326084