This article is from the Recreational Figure Skating FAQ, by Karen Bryden with numerous contributions by others.
The potentially most sinister type of injury is a concussion. Always
try to tuck your head when falling so you don't hit it, but if you do
and you either suffer a period of unconsciousness or are dizzy or
disoriented after you get up, get off the ice and have someone drive
you to a doctor. This is not something you should take lightly.
Chances are it's nothing, but evaluation, close monitoring and timely
reaction greatly minimize the consequences if it's something serious -
why take a risk?