There are inconsistent approaches to how medicine is administered to pupils in Scotland, and "limited focus" on the rights of the children in question, according to information obtained under the Freedom of Information Act.
Children's commissioner Tam Baillie found that many local authorities had done little to build on legislation from more than a decade ago, after he surveyed all 32 councils and received responses from all but one.
His report, The Administration of Medicines in Schools, finds some good practice across Scotland, but also "a great deal of variation".
"This is particularly apparent in the area of involving children in decisions affecting them and around consent," the report's conclusion states.
Local policies "appear to have a limited focus on the rights of children and young people".
And there is "a considerable amount of confusion around the age of legal capacity and the idea of consent".
Falkirk, for example, said: "It would generally be assumed by a qualified medical practitioner that at age 12 the child is capable of consenting."
But West Lothian stated: "No pupil under 16 should be given medication without his or her parent's written consent."
Eleven authorities advised that any child or young person could consent if a medical professional deemed him or her capable of understanding the implications of treatment.
There are similar disparities in relation to the administration of non-prescription medicine. Many authorities "rely heavily" on national guidance published in 2001.
But Mr Baillie wants to see a review of the guidance to take account of changes to policy, legislation and current thinking on self-administration of medicine.