Vomiting after a head injury: when should you be concerned?

Emergency numbers
United States: 911
United Kingdom: 999 or 112
European Union: 112
Elsewhere: your local emergency number

Short answer. After a blow to the head, any vomiting warrants an immediate call to emergency services for guidance on medical care, even if there has only been one episode. This reflects the French public guidance used here and does not automatically mean a serious injury is present. Repeated vomiting or worsening alertness further increases the need for emergency care. The decision to perform a CT scan rests on medical assessment, not on counting vomiting episodes yourself.

Important. Vomiting after a blow to the head is a warning sign: call emergency services for urgent guidance on the appropriate care, in keeping with the French public guidance used here. Do the same if the person becomes difficult to wake, increasingly confused, has a seizure or develops another neurological sign. Do not wait for several symptoms to occur together.

Why does this symptom deserve particular attention?

After a blow to the head, someone may feel nauseated or vomit as part of a concussion. Other causes are possible. The symptom alone therefore does not reveal what is happening in the brain. What matters is the overall situation: the force of the impact, level of consciousness, headache, memory, balance and how symptoms change.

For example, someone gets up after a fall, vomits once, then seems better. That does not establish that everything is fine. Call emergency services immediately for guidance on medical care, explaining when the injury happened, the vomiting episode and any other signs. If they vomit again, become confused or more drowsy, the urgency is even clearer.

One episode or several: what is the difference?

NICE guidelines recommend referral to an emergency department after any vomiting episode following a head injury, within the context of their assessment criteria. However, the thresholds professionals use to decide on imaging are more specific and differ according to age and other factors. In the UK’s NICE guidelines, more than one vomiting episode is among the criteria for an urgent CT scan in people aged 16 or over. In children, decisions take account of a combination of criteria and possible medical observation.

This distinction is crucial: a CT scan rule is not permission to stay home while waiting to reach a particular number of episodes. Members of the public should not count vomiting episodes to make this decision themselves.

Which accompanying signs should prompt an emergency call?

After any vomiting following a head injury, call emergency services immediately. Also report any of the following signs if present:

• difficulty staying awake or difficulty waking the person;

• increasing confusion, unusual behaviour or new difficulty speaking;

• weakness in an arm, a leg or one side of the face;

• a seizure;

• a headache that worsens and does not go away;

• pupils that are clearly different in size or another new neurological problem.

An injured person may not notice that their answers are less clear or that they are unusually drowsy. Observations from those close to them then become particularly useful.

What should you prepare for the call or assessment?

Four pieces of information help describe the situation without making your own diagnosis:

1. When the impact happened and the circumstances: a fall, an accident or a forceful impact.

2. Vomiting: when the first episode occurred, the approximate number, and whether it has continued or returned after an improvement.

3. Other changes: headache, alertness, memory, balance, speech and behaviour.

4. Context: age, anticoagulant or antiplatelet medication, a known bleeding disorder or any other possible injury.

You do not need all this information before calling. If the person’s condition is deteriorating, the call comes first. Also mention difficulty keeping down usual medicines or fluids, but do not let this distract from neurological assessment.

What about children?

A young child cannot always explain nausea, a headache or a memory problem. Vomiting after a head injury, unusual irritability, inconsolable crying, difficulty feeding or abnormal drowsiness calls for particular vigilance and appropriate medical advice. In infants, changes in behaviour and feeding may be the most visible signs. In France, any vomiting after the injury warrants an immediate call to emergency medical services for guidance on care.

Paediatric observation and CT scan criteria must not be replaced by a simplified rule intended for adults.

Key points: after any vomiting following a head injury, contact emergency services immediately for guidance on medical care. Repeated vomiting, abnormal drowsiness or a neurological problem increases concern. Do not wait for a second episode before seeking advice. The CT scan decision is a medical one.