**The handle is a plausible trigger, but your observation cannot yet distinguish an allergy from irritation.** The rash’s location and improvement after changing knives are useful clues. I couldn’t find a published report specifically identifying Victorinox Fibrox handles as a cause of dermatitis.

Victorinox lists current Fibrox handles as **thermoplastic elastomers (TPE)**. That describes a family of materials; the specification does not disclose the complete formulation or establish what is in your older handles. [Victorinox product specification](https://www.victorinox.com/en-CH/Products/Cutlery/Bread-Knives/Fibrox-Bread-and-Pastry-Knife/p/5.2933.26BK)

Two explanations are worth investigating:

- **Irritant contact dermatitis.** Friction from the textured grip, combined with sweat or detergent exposure, could aggravate existing eczema at those contact points. People with atopic eczema are particularly susceptible to irritation. [DermNet: irritant contact dermatitis](https://dermnetnz.org/topics/irritant-contact-dermatitis)
- **Allergic contact dermatitis.** A handle ingredient or substance on its surface could be responsible. Contact allergy can develop after years of exposure, so your long history with these knives does not exclude it. The exact substance would need investigation. [DermNet: allergic contact dermatitis](https://dermnetnz.org/topics/allergic-contact-dermatitis)

Your latex intolerance is relevant history, but it does not establish an allergy to TPE. Immediate natural-latex allergy usually involves latex proteins; delayed eczema associated with rubber products often involves manufacturing chemicals. **There is no evidence here that your handles contain those particular chemicals.** [DermNet: latex allergy](https://dermnetnz.org/topics/latex-allergy)

For now, keep using the handles your skin tolerates and photograph the improvement. Arrange a dermatology review and ask about **patch testing**, which investigates delayed contact allergy. Bring the knife’s model information and photos; the dermatologist can decide whether testing handle material would help. Patch testing does not diagnose friction-related irritation. [DermNet: patch tests](https://dermnetnz.org/topics/patch-tests)

Also ask Victorinox for the material and additive information for your specific models, mentioning your suspected contact dermatitis and latex history. Avoid deliberately provoking another flare, and discuss any change to your prescribed corticosteroid schedule with your clinician.