All patients presenting to A&E with a head injury should be assessed by a trained member of staff within 15 minutes of arrival at hospital, according to NICE.
The institute has updated its guidance, first published in 2003, on the early care of adults and children with head injuries.
For patients with specified risk factors, CT imaging of the head should be performed and results analysed within one hour of the request having been received by the radiology department, the revised guidance adds.
Additionally, children aged under 10 who are in a coma should have CT imaging of the cervical spine within one hour of presentation or as soon as they are sufficiently stable.
Peter Littlejohns, NICE clinical and public health director, said: 'Around 750,000 people with a head injury are seen at hospital emergency departments each year.
'This guideline gives updated recommendations based on new evidence, as well as some new advice, which should ensure that health professionals can deliver the best possible care to all patients with head injury,' professor Littlejohns added.