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Allergic Contact Dermatitis

Allergic Contact Dermatitis

What is Allergic Contact Dermatitis?

Allergic contact dermatitis (ACD) is a red, itchy rash that develops after exposure to an allergen.  Allergens are substances found in the environment that come in contact with the skin inducing a delayed hypersensitivity reaction (allergic rash that appears a few days after exposure).  The rash often appears geometric or linear with sharp borders.  This appearance suggests that something came in contact with the skin.  Sometimes the rash may even blister but typically only occurs where the offending substance touched the skin.  There are exceptions to this, as some allergens can be ingested causing a full body rash (systemic contact dermatitis).

While ACD is more commonly found in adults and teens, it can sometimes occur in infants and small children.  In fact, anyone can develop a sensitivity to an allergen, and it may occur at any time.  This is true even if a person was not previously allergic to a specific substance or product.

What Causes Allergic Contact Dermatitis?

ACD is an immune system reaction.  A person must be previously exposed (usually by skin contact) to an allergen in order to become sensitized.  Sensitization is the body’s immune system reacting against the external substance.  This immune reaction causes a rash, which typically occurs 24-48 hours after exposure to an allergen.  Once a person is sensitized, the immune system “remembers” the offending allergen and will react with a rash every time it is exposed.

Allergens can be found everywhere in the environment and commonly include:

  • Skin and hair care products (preservatives, fragrances, dyes)
  • Jewelry, metal snaps and belt buckles (nickel, cobalt and gold)
  • Medications (Antibiotic creams, ear/eye drops, topical steroids)
  • Clothing/shoes (textile dyes, formaldehyde, rubber accelerators)
  • Plants (poison ivy, flowers and resins)

How Do You Treat Allergic Contact Dermatitis?

For mild allergic rashes, you may use cool compresses and over-the-counter anti-itch treatments such as antihistamines and hydrocortisone 1% cream.  However, for more severe and widespread allergic contact dermatitis you should see a dermatologist or other physician.  The doctor will often prescribe a topical steroid cream, antihistamine pills or in some situations oral prednisone.  These treatments will improve the symptoms and make the rash go away sooner.  If the rash is untreated, it usually resolves on its own in about 2-4 weeks (assuming you avoid continued exposure to the allergen).  However, you should seek immediate medical attention if you think the skin is infected (pus, pain, or streaking redness), your eyes are red with problems seeing, or your airway passages are inflamed causing difficulty breathing.  These reactions are rare but can be very serious.

Once an allergen is identified, try to avoid exposure.  Prevention is key and includes the following steps:

  • Avoid the allergen completely when possible.
  • Wash the skin thoroughly with mild soap and water after exposure.
  • Wash off clothing and equipment that may have the allergic substance on them.
  • Wear protective clothing and gloves when around the allergen.
  • Apply a protective barrier cream prior to potential exposure such as IvyBlock to prevent or lessen rash from poison ivy
  • Cover potential nickel sources such as snaps and buttons with an iron-on patch.
  • Take care around pets as they may have allergic substances such as poison ivy on their fur, which can transfer to people.

Sometimes it is difficult to identify the allergen and avoid exposure.  A dermatologist can be helpful by looking at the rash and getting a detailed history of potential allergen exposures.  It may even be necessary to do Patch Testing (a type of allergy testing) where panels are applied to the back.  These are left in place for 48 hours and then removed in the dermatologist’s office.  By looking at the skin reaction to the various patches, the dermatologist can identify what allergies you have and how to avoid them.  For further information, make an appointment with a dermatologist at Iowa Dermatology Consultants.

Additional Allergic Contact Dermatitis Resources

Links to Additional Information:

American Academy of Dermatology Psoriasis Videos:

Why Iowa Dermatology Consultants?

Iowa Dermatology Consultants believes in a patient focused approach to care.  We work with patients forming an active partnership in treatment to help repair the physical and emotional damage of skin disease.  Our Ankeny and Ames locations allow us to conveniently treat patients across the Des Moines metro area and all of Central Iowa including Ames, Carroll, Fort Dodge, Iowa Falls, Marshalltown, Huxley, Slater, and Indianola.  

At Iowa Dermatology Consultants, all of our physicians are board-certified dermatologists. Your care provided by Dr. Snider, Dr. Smith, or Dr. Myers is founded in knowledge and experience which exceeds that of a general practitioner.  Together they have almost 50 years of combined experience in diagnosing and treating a vast array of skin conditions.  This includes over 16,000 hours of patient care training to ensure that a board-certified dermatologist can expertly diagnosis and treat over 3000 dermatologic conditions.

Whether you’re coming to us for help with skin cancer or diseases like acne, psoriasis, and eczema; or to reverse the signs of aging with Botox, chemical peels or other cosmetic procedures, at Iowa Dermatology Consultants you will be getting the best dermatologic care in Central Iowa.