If a child needs medication urgently, say if their parent is on the way but they are in pain, I get written permission by text along with time last given... then parents must sign it when they arrive;
If a child is prone to eg convulsions, then I would have written permission in place already as I have been told my medical experts that in these cases it is more important to get the fever reducing syrup in rather than waiting for parents to contact me back, then to ring 999 if the temp continues to rise. As Ofsted see this as a serious incident, I would then ring them to inform that I had called 999;
If children need teething relief, eczema cream, inhaler etc then I have a blanket coverage signed by parents, training where necessary eg for Epipens and I inform them in the child's daily diary that it has happened and when... for the inhaler and any steroid creams, I also complete a medication form.
Oh, I am a childminder. Hope this helps