NaillyHEMA is the small, reactive molecule that lets gel polish cure into a hard film. Fully cured, it is inert; uncured product touching skin is how sensitisation happens — and once you are allergic, it is for life, with cross-relevance to dental composites and medical adhesives that share the chemistry.
Prevention is craft: product kept off skin, full curing in the system's own lamp, immediate cleanup of contact. HEMA-free lines exist for the sensitised, guided ideally by dermatologist patch testing.