Question

Why after getting injured there is a vomitting tendency?

Answer 1

It means that the head injury is serious

You should call an Ambulance and be taken to hospital for investigation - most likely X-Ray followed by whatever is indicated (CAT scan, MRI etc)

No period of unconsciousness should ever be ignored and vomiting after a head injury is a serious sign - so is blurred vision, slurred speech, unconsciousness staggering or inability to recall/recognise known people (orientation to person place or time)

Hospitals have manadatory periods of observation for head injuries - usually around four hours of half hourly obs (pulse, blood pressure, pupil reactions etc). All of this is because a head injury has the possibility of developing into a medical emergency sometimes slowly and sometimes quickly.

Basically the head is a box of bone (the skull) containing the brain. There are few exits from that box of bone - the eyes, the ears and the hole at the bottom that the spinal cord goes out (formanen magnum). Any swelling of the brain from injury - either from bruising or actual bleeding- means that the space is being taken up be something that is not meant to be in there. Sometimes called in medicine a Space Occupying Lesion (SOL)

The end result is an increase in intracranial pressure i.e. the pressure inside the box of bone and therefore the pressure on the brain. This cause the brain to try to exit the box of bone either by the existing holes or via the hole that caused the trauma (gunshot or blunt head wound). Having bits of your brain trying to be somewhere other than comfortably within your skull is never a good thing and rarely has a good outcome.