**The handle could plausibly be aggravating your eczema, but that does not establish an allergy to Fibrox.** I didn’t find a documented Fibrox-specific dermatitis problem in the sources I searched.

Victorinox identifies current Fibrox handles as **thermoplastic elastomer (TPE)**—a family of rubber-like synthetic materials. That description does not identify every ingredient or establish the composition of your decades-old handles. [Victorinox product specifications](https://www.victorinox.com/en-PL/Products/Cutlery/Chef%27s-Knives/Fibrox-Chef%E2%80%99s-Knife/p/5.2033.19B)

Two explanations are plausible:

- **Irritant contact dermatitis:** friction from the textured grip, pressure, sweat, or cleaning residues could aggravate already vulnerable skin. The two contact spots you describe fit this possibility. Friction, sweating, and detergents are recognised eczema triggers. [DermNet](https://dermnetnz.org/topics/irritant-contact-dermatitis)
- **Allergic contact dermatitis:** you could be reacting to an ingredient in the handle or something deposited on it. Rubber-manufacturing chemicals can cause delayed eczema, including from handgrips—but that does **not** mean those chemicals are present in Fibrox. [DermNet](https://dermnetnz.org/topics/allergy-to-rubber-accelerators)

Your latex intolerance does not settle the question. Allergy to natural-latex proteins and delayed allergy to manufacturing chemicals are different reactions; a rubber-like feel alone does not imply latex exposure. [DermNet’s latex explanation](https://dermnetnz.org/topics/latex-allergy)

The improvement after switching knives is a useful clue, although three or four days cannot distinguish allergy, friction, and ordinary eczema fluctuation. **Keep using the handles you tolerate, and bring this observation to your dermatologist.** Ask about **patch testing**, which investigates delayed contact allergy rather than the immediate reactions assessed by skin-prick testing. Photos, knife model numbers, and information from Victorinox about the particular handle formulation could help guide testing. [American Academy of Dermatology](https://www.aad.org/public/diseases/eczema/types/contact-dermatitis/patch-testing-rash)

Discuss the improvement with your prescriber before changing your corticosteroid schedule.