Most gel brands now advertise TPO and HEMA free. It is worth knowing what each one is, because the two are avoided for genuinely different reasons.

HEMA and contact sensitivity

HEMA is a small monomer used to help gel adhere. Because the molecule is small, uncured product can pass through skin, and repeated exposure can cause an allergy that does not fade. Once a technician develops it, they usually react to every HEMA-containing product afterwards.

This is an occupational risk more than a consumer one. Someone getting their nails done monthly has limited exposure. Someone doing eight sets a day, five days a week, does not.

TPO and regulation

TPO is a photoinitiator - the ingredient that makes gel cure under a lamp. It has been reclassified in the EU and is being removed from cosmetic formulations there. Reformulating without it is a compliance matter as much as a safety one.

What it changes in practice

Modern HEMA-free formulas cure and wear as well as the ones they replaced. That was not true a few years ago, and it is the reason the switch is now straightforward.

None of this removes the need for good practice. Avoid skin contact with uncured product, keep the workspace ventilated, and cure fully. Cleaner formulations lower the risk; they do not eliminate it.