If you experience itchy, red skin after coming into contact with an irritating substance, chances are you have contact dermatitis.

The two most common types of contact dermatitis occur when your skin is exposed to something that you’re especially sensitive to or that you’re allergic to. This first type is known as irritant contact dermatitis. The second is known as allergic contact dermatitis.

If you have allergic contact dermatitis, then your body will trigger an immune system response that makes the skin itchy and irritated.

Examples of substances that cause allergic contact dermatitis include:

Irritant contact dermatitis is mostly caused by toxins, such as detergents and chemicals in cleaning products. It can also result from repeated exposure to nontoxic substances.

Soap is an example of a substance that can cause either allergic contact dermatitis or irritant contact dermatitis.

Allergic contact dermatitis doesn’t always cause a skin reaction right away. Instead, you may notice symptoms that take place anywhere from 12 to 72 hours after exposure.

Symptoms associated with allergic contact dermatitis include:

These symptoms can last anywhere from 2 to 4 weeks after exposure.

There’s a difference between an allergic reaction that could affect your breathing — known as an anaphylactic reaction — and an allergic contact dermatitis one.

Serious allergic reactions involve the body releasing an antibody known as IgE. This antibody isn’t released in allergic contact dermatitis reactions.

If you have a skin rash that just won’t go away or have skin that feels chronically irritated, make an appointment to see your doctor.

If these other symptoms apply, you may also need to see your doctor:

  • You have a fever or your skin’s showing signs of infection, such as being warm to the touch or oozing with fluid that isn’t clear.
  • The rash distracts you from your daily activities.
  • The rash is becoming more and more widespread.
  • The reaction is on your face or genitalia.
  • Your symptoms aren’t improving.

If your doctor thinks allergic contact dermatitis may be to blame, they can refer you to an allergy specialist.

An allergy specialist can perform patch testing, which involves exposing your skin to small amounts of substances that commonly cause allergies.

You’ll wear the skin patch for about 48 hours, keeping it as dry as possible. After a day, you’ll return to your doctor’s office so they can look at the skin exposed to the patch. You’ll also come back about a week later to further inspect the skin.

If you experience a rash within a week of exposure, you likely have an allergy. Some people may experience an immediate skin reaction, however.

Even if your skin doesn’t react to a substance, you can be on the lookout for substances that commonly cause your skin to be irritated. Some people keep a journal of their skin symptoms and determine what they were around when the reaction occurred.

Your doctor can recommend allergic contact dermatitis treatments based on what’s causing your reaction and its severity. The following are some examples of common treatments.

For mild reactions:

  • antihistamine medications, such as diphenhydramine (Benadryl), cetirizine (Zyrtec), and loratadine (Claritin); these may be available over the counter or with a prescription
  • topical corticosteroids, such as hydrocortisone
  • oatmeal baths
  • soothing lotions or creams
  • light therapy

Shop for antihistamines, such as diphenhydramine, cetirizine, and loratadine.

Shop for hydrocortisone.

For severe reactions causing facial swelling, or if the rash covers your mouth:

  • prednisone
  • wet dressings

Shop for wet dressings.

For an infection:

  • antibiotics

Avoid scratching your rash because scratching can cause infection.

Once you determine what’s causing your allergic contact dermatitis, you should avoid that substance. This will often mean you must take great care when reading labels for skin care products, household cleaners, jewelry, and more.

If you suspect that you’ve come into contact with any substances you may be allergic to, wash the area with soap and lukewarm water as quickly as possible. Applying cool, wet compresses may also help soothe itching and irritation.

Avoiding the allergen as much as possible is the only way to keep your skin from becoming itchy and irritated. If you experience severe symptoms, you should see your physician.

Healthline and our partners may receive a portion of revenues if you make a purchase using a link above.