This topic is about a person who has been using Hollister ostomy products for nearly seven years without any issues but suddenly developed a severe skin irritation under the barrier. Despite trying various skin-care remedies and consulting with numerous healthcare professionals, the cause of the irritation remains unidentified. The person is curious if it's possible to develop an allergy to ostomy materials after years of use and is seeking advice from others who might have experienced a similar situation.

Here are some helpful insights and advice:

1. Even if the product codes remain the same, manufacturers might change suppliers, manufacturing processes, or adhesives, which can lead to new reactions. Trying a different brand or model can help determine if the product is causing the issue.

2. Delayed adhesive allergies can occur over time:
- Some users may develop sensitivity specifically to the adhesive layer of a barrier or wafer.
- To test for an allergy, press on the reddened area. If the redness does not blanch (stay red), an allergy is more likely. If it blanches (turns white), the irritation might be mechanical, such as from a shaving rash or ingrown hairs.

3. Switching brands has helped others resolve similar issues. For example, one person developed an allergy to Hollister pouches after ten years and switched to Coloplast products, which stopped the skin inflammation.

4. If changing products resolves the reaction, keep in mind that any brand can later change materials. It's a good idea to document lot numbers and keep samples for future comparison.