Contact Allergy (Contact Dermatitis & Allergic Reactions)

A contact allergy occurs when the skin reacts to a substance it comes into direct contact with, triggering an immune response. This reaction is known as allergic contact dermatitis (ACD) and is caused by delayed hypersensitivity (Type IV reaction) mediated by T-cells.

Common Causes of Contact Allergy:

1. Metals (Nickel, Cobalt, Chromium) – Found in jewelry, watches, and belt buckles.

2. Fragrances & Preservatives – Present in perfumes, lotions, shampoos, and cosmetics.

3. Rubber & Latex – Used in gloves, balloons, and medical devices.

4. Hair Dyes (PPD – Para-phenylenediamine) – Found in hair coloring products.

5. Plants (Poison Ivy, Poison Oak, Poison Sumac) – Contains urushiol, a common allergen.

6. Medications (Topical Antibiotics like Neomycin, Benzocaine) – Used in ointments and creams.

7. Household Chemicals (Detergents, Cleaners, Formaldehyde) – Found in cleaning and industrial products.

Symptoms of Contact Allergy:

• Redness, swelling, and itching at the site of contact.

• Blisters, dry patches, or cracked skin.

• Burning or stinging sensation.

• Symptoms may take 24-72 hours to appear after exposure.

Diagnosis: Patch Testing

• A patch test is used to identify specific allergens.

• Small amounts of potential allergens are applied to the skin (usually on the back).

• The skin is checked for reactions 48 and 72 hours later.

Treatment & Management:

✅ Avoid the allergen once identified.
✅ Topical steroids (e.g., Hydrocortisone, Betamethasone) to reduce inflammation.
✅ Oral antihistamines (e.g., Cetirizine, Loratadine) for itching relief.
✅ Moisturizers to repair the skin barrier.
✅ Barrier creams or gloves for protection against irritants.