Any child under one year of age who experiences head trauma should always be seen by the doctor because signs of injury are harder to detect in a young infant. If your child is motionless or unconscious, blood or fluid oozes from the ears or nose, there is bruising around the eyes or behind the ears, or she acts lethargic or refuses to move after his fall, you should call 911 right away. Also, if you suspect your child has a skull or spinal injury (he fell from a distance greater than his standing height, was in a car or bike accident, or is not fully alert), call 911. Don't move him unless he's in harm's way; stabilize his head, neck and spine as best you can until help arrives.          

 For kids older than 12 months, you can take a watch-and-wait approach. If your child is crying but can get up and is moving about, he's probably just fine. Screaming is a perfectly healthy reaction and rarely does the size of the bump that may result from a head knock have anything to do with the extent of the injury. (There are loads of blood vessels in the head and face, so the swelling can be dramatic.)                                                                                                                                 

Fortunately, the vast majority of head bumps don't require a trip to the doctor -- just hugs, some ice if your child will tolerate it (wrapped in a towel), and close observation on your part. If you see any of these signs, however, head to the doctor or ER:

• There's a lot of bleeding Because of all the blood vessels in the scalp, cuts on the head can bleed quite a bit and often need stitches. Profuse bleeding that’s difficult to staunch or that soaks a towel is a lot.
• The bump is large or has a soft feel to it. If so, the doctor may want to see him.
• There's clear fluid coming from her ears or nose.
• He has severe or persistent vomiting. A little nausea, and vomiting once, probably because he's upset, can be normal, but by all means get him checked out if you're worried.
• He's excessively sleepy. Being groggy after a head bump is common and fine, but if it's hard to wake him or he doesn't perk up after a brief nap, that's not okay.
• He has a bad headache. Bumps to the head hurt, of course, but if your child has so much pain that he's inconsolable, it's not normal.
• He feels dizzy or weak, or has trouble walking, talking, or seeing. Also be alert for changes in behavior, like unusual irritability.