What is allergic contact dermatitis?

Young woman scratching her elbow. Allergic contact dermatitis symptoms may appear within hours or over weeks or months.

If you’re experiencing an irritating rash after wearing your favorite necklace or earrings, you could have allergic contact dermatitis. Allergic contact dermatitis is a type of inflammatory skin condition. It’s also known as a contact allergy because it’s caused by a reaction to an allergen touching your skin.

Some symptoms appear within a few hours after contact. But long-term symptoms may take weeks or months to develop if you repeatedly encounter the allergen. Treatment usually involves a mix of avoiding the allergen and taking medication to relieve symptoms as and when they appear.

In this article, we begin by outlining common allergic dermatitis triggers and symptoms. Later, we discuss how it’s diagnosed and treated.

What triggers allergic contact dermatitis?

Symptoms usually start to appear over time, after repeated contact with your trigger. Some people may develop contact dermatitis symptoms sooner than others. This can happen if they have other allergies.

Common triggers include:

  • Nickel: jewelry, cell phones, foods and e-cigarettes
  • Plants: Poison ivy, poison oak and poison sumac (urushiol in the sap), ragweed (via airborne contact dermatitis)
  • Latex: rubber bands, gloves and balls, balloons, condoms and diaphragms
  • Balsam of Peru (Myroxylon pereirae): food and drink flavoring, a fragrance in cosmetics and toiletries, and medicinal products including creams and lotions

Allergic contact dermatitis symptoms

When an allergen makes contact with your skin it can trigger an allergic response. But it does not involve Immunoglobulin E (IgE) antibodies. So, no sneezing or running nose like you’d get with hay fever, for example. Rather, this contact allergy happens when other cells in your immune system are activated. These are T cells, which are a type of white blood cell.

Some weed allergies
can give you a rash

Four different types of weeds that can cause hay fever. Some, like ragweed and mugwort may also give you an itchy rash.

Early symptoms can include:

Early symptoms can include:

  • Rash and itching
  • Redness; darker skin types may have areas of deep brown or purple skin (hyperpigmentation), sometimes darker skin may appear ashen grey (hypopigmentation)
  • Swelling
  • Bumps or blisters, sometimes filled with clear fluid

These symptoms usually happen within hours but may also take a day or two to appear.

Long-term symptoms of allergic contact dermatitis

More long-term symptoms may include:

  • An eczema-like rash
  • Thickened skin
  • Scaling or cracked skin (from scratching)

Prevention tips for allergic contact dermatitis

Avoiding your contact allergen usually reduces flare ups and is an important part of symptom management.

These steps may help if you have sensitive skin:

  1. Choose household and personal care items that are hypoallergenic and fragrance-free
  2. Use protective clothing such as gloves when necessary
  3. Wear cotton clothes since they’re gentler than other fabrics
  4. Wash new clothing before wearing it and avoid scratchy materials
  5. Regularly moisturize your skin with emollients to seal in moisture

Can I get rid of allergic contact dermatitis?

There isn’t a cure, but symptom-relieving medication may help reduce symptoms. For particularly itchy skin, over-the-counter antihistamine tablets and mild (1% or lower) topical corticosteroids could be suitable options. Both are available without a prescription. But if your skin is still itchy and inflamed you may need a stronger prescription treatment. Please do speak to your healthcare provider about this.

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For severe allergic contact dermatitis, you could be prescribed corticosteroids taken by mouth or given by injection. These reduce inflammation and help treat symptoms that cover large areas of the body. But they are usually only prescribed for short periods of time.

Home remedies for allergic contact dermatitis

Applying a cold compress and calamine lotion or taking an oatmeal bath can help soothe symptoms. These home remedies may stop you scratching and breaking the skin, which can cause infection.

How is allergic contact dermatitis diagnosed?

Speak to your healthcare provider if you have a rash and aren’t sure what’s causing it. It’s a good idea to note down when you get symptoms, take a photo of the affected area and any other important information. For example, how quickly the rash develops and any relevant family medical history, such as skin conditions and allergies.

The location of the rash may also help your healthcare provider diagnose potential allergens:

  • Ear lobes and neck – associated with wearing nickel-based jewelry
  • Face and eyelids– from applying cosmetics that contain allergens such as Balsam of Peru
  • Hands – from wearing latex gloves, handling coins containing nickel or using allergen-containing soaps

A positive patch test is usually needed to confirm a diagnosis. Patch testing involves taping small patches dabbed in suspected allergens to your back and checking for a reaction. It usually takes two days, or more, for the results to show.

What is photo-allergic contact dermatitis?

Some allergens only cause inflammation with sun exposure. So, you may notice you get a rash from sunscreen on a sunny day. This can also happen with other allergens, such as shaving lotion and some perfumes. Patch testing can help identify products that cause this reaction.

Did you know...?

  • If you get an itchy skin rashon your hands after handling money it could be from the nickel in coins. Why is nickel used? It’s light, resistant to corrosion, easy to stamp and very cost-effective.
  • Products that smell like cinnamon could contain Balsam of Peru. Balsam of Peru comes from the trunk of a tree grown in Latin and Central America and can trigger allergic contact dermatitis in some people. Look out for it in toiletries, essential oils, cosmetics and flavorings.
  • Burning poison ivy, poison oak or poison sumac can cause severe allergic respiratory symptoms if inhaled. This is because urushiol, the rash-causing sap, can be carried in the smoke from burning leaves or brush.
  • Giant hogsweed contains a toxic sap that can cause severe skin irritation. Contact with the leaves or sap can trigger photo-allergic contact dermatitis (also known as phytophotodermatitis). This is where the skin blisters if exposed to sun. It can even cause blindness if the sap gets in your eyes.

Who is more at risk of allergic contact dermatitis?

Those most at risk of developing allergic contact dermatitis include:

  • People in specific occupations: Metalworkers, beauticians, hairdressers, healthcare workers, cleaners, painters, gardeners and agricultural workers due to frequent allergen exposure.
  • Children: Many young children have nickel allergy.
  • Older people: Topical medication contact allergy is more common in the elderly.
  • People with a history of atopic dermatitis: This is the most common form of eczema.

How is irritant contact dermatitis different from allergic contact dermatitis?

Irritant contact dermatitis is non-allergic. It can affect anyone, especially after repeated exposure to the irritant. Substances like abrasive cleaning chemicals and laundry detergents can cause it. Allergic contact dermatitis only affects people who respond to an allergen, for example nickel.

Allergic contact dermatitis may take a day or two to appear. Irritant contact dermatitis can flare within minutes.

But why the time delay? Allergic contact dermatitis is a Type IV allergic reaction (remember those T cells we mentioned). Type IV allergic reactions tend to be slower, with symptoms usually appearing between 12 and 72 hours after exposure.

Most of the allergies we cover are Type I, which involves IgE antibodies, for example hay fever. In comparison, hay fever symptoms usually develop immediately or very soon after encountering the allergen pollen.


Allergic contact dermatitis is a reaction to an allergen touching your skin. It usually causes an itchy rash that may take a day or two to appear. Various substances can trigger it such as nickel, latex or fragrances in cosmetics and toiletries. Most cases can be treated with over-the-counter medicines or simple home remedies.

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