You need written consent
You need to get written consent from parents/carers before you give a child under 16 any medication.
This applies to all cases, except in 'exceptional circumstances' where the medicine has been prescribed without the knowledge of the parents (e.g. contraceptives). In this case, you should encourage the pupil to involve their parents while respecting their right to confidentiality.
Bear in mind that you should only administer medicine at school when it would be detrimental to a child’s health or school attendance not to do so.
This is outlined in the DfE's guidance on supporting pupils with medical conditions at school (page 20). The guidance is statutory for maintained schools, academies (including alternative provision academies) and PRUs, and a useful reference for other settings, such as independent schools.
Does email count as written