Traditional head lice treatments which poison the lice, Full Marks Solution Spray has a physical action on the lice causing them to dehydrate (lose water) and die. They can then be removed along with any eggs using the fine metal toothed Full Marks Removal Comb provided. If a member of your family needs treatment with Full Marks Solution Spray you should also check other members of your family for live lice with a specially designed Full Marks Detector Comb and treat if necessary.