Allergic dermatitis reactions to peristomal products may not develop on first exposure because:

• A. They always occur on first exposure
• B. They may develop after repeated exposures or cross-sensitization
• C. They occur only with bacterial infection
• D. They are not influenced by prior exposures

Answer: (B)

Allergic contact dermatitis to peristomal products arises from a delayed, sensitization-based immune response. The first exposure often primes the immune system without noticeable symptoms. With repeated exposures, memory T cells recognize the allergen and trigger inflammation, producing the itching, redness, and rash around the stoma. Cross-sensitization can occur when related substances share allergenic components, so a dermatitis may appear with a product that’s similar to the one that first sensitized the person. This explains why reactions may develop after repeated use or after exposure to a related product. Immediate reactions on first exposure are not typical, and illness from infection is not what drives this dermatitis, nor is it accurate to say prior exposures don’t matter.