thanks, for a moment there I was looking for a like button!
Snufflebabe - FAQ is the mildest paraffin or camphor based product I've found and although the dough doesn't require a great quantity it absolutely must be risk assessed, even then constant supervision is necessary to ensure the dough isn't eaten.
Known allergies should already be recorded and considering how unusual in would be for vapour rub to be kept in a setting, planning the activity would indeed involve buying it, sharing what's to happen with parents, checking current health status and securing written permission in advance. It depends how much the playdough idea is valued as to it actually occurring.
For anyone wanting to report adverse reactions to any medicine the
yellow Card scheme can be accessed through Gov.uk where a home nation needs to be selected.
About allergies on NHS