Most bumps to the head are exactly what they look like. A small proportion involve bleeding inside the skull, and that bleeding declares itself over the following hours while the person appears to be recovering.
That delay is the whole reason this page exists.
The thing that makes head injury different
With most injuries, the first assessment tells you how bad it is. With a head injury it does not.
Bleeding inside the skull takes time to accumulate. Someone can be knocked out briefly, get up, walk about, chat, seem fine, and deteriorate two hours later as the pressure builds. That pattern, a lucid interval followed by decline, is the classic presentation of an extradural haematoma, and it is precisely the case where prompt surgery saves a life.
And concussion symptoms can take up to 48 hours to appear. Someone who seems completely normal on the evening of the injury may be badly symptomatic the next day.
So the useful thing here is not a clever assessment on the spot. It is watching, for long enough, and knowing what you are watching for.
Ring 999 for any of these
Recognising concussion
Concussion is a functional brain injury without visible structural damage. You do not have to be knocked out to have one, and most people with concussion never lose consciousness at all.
| Category | Signs |
|---|---|
| Thinking | Confusion, feeling foggy, slow to answer, poor concentration, memory gaps around the event |
| Physical | Headache, dizziness, nausea, balance problems, blurred vision, sensitivity to light and noise, fatigue |
| Emotional | Irritability, tearfulness, anxiety, feeling "not right" |
| Sleep | Sleeping much more or much less, trouble getting to sleep |
Memory loss around the event is a useful marker. Ask what they remember immediately before and immediately after. A gap of more than a few minutes either side is significant.
"Feeling not quite right" is a genuine symptom and should be taken seriously rather than dismissed, particularly in someone who is normally unbothered by things.
The first hours
For a head injury with none of the emergency signs above:
- Sit them down and keep them still.
- Apply a cold compress wrapped in cloth to any swelling. A dramatic egg-shaped lump on the scalp is common and is not itself a worrying sign.
- Control any bleeding with direct pressure around the wound rather than on any depression. Scalp wounds bleed dramatically out of proportion to their seriousness.
- Paracetamol for headache. Avoid ibuprofen and aspirin for the first 24 to 48 hours, since both affect clotting and could worsen a bleed.
- No alcohol.
- Rest, somewhere quiet, with the lights low.
- Someone stays with them for at least 24 hours.
The watch
The most useful thing you can do, and the part that needs saying explicitly because it takes discipline.
Somebody stays with them for at least 24 hours, and checks:
- Can they be woken easily and do they respond normally?
- Do they know who and where they are?
- Is the headache the same, better, or worse?
- Have they vomited, and how many times?
- Are the pupils equal?
- Any weakness or numbness?
- Any change in behaviour, however slight?
Write down the time of the injury and check in at intervals, noting what you find. Under stress, and over hours, memory is unreliable about whether someone is worse than they were.
The trend is the signal. Any deterioration, at any point, means emergency help. Getting gradually better over hours is reassuring. Getting worse in any respect is not, however minor it seems.
Recovery
Most concussion resolves in one to two weeks. Recovery is not passive and there are things that measurably help.
- Rest for the first 24 to 48 hours, physically and mentally. Low stimulation, low screens, low noise.
- Then reintroduce activity gradually, staying just below the level that brings symptoms on. Complete rest beyond the first couple of days actually slows recovery, which reverses older advice.
- No return to anything with a risk of a second head impact until fully symptom-free. This is not caution: a second concussion before the first has healed can cause disproportionate and lasting damage, and in rare cases is catastrophic.
- Expect it to take longer than you want, and expect symptoms to come and go.
- Seek help if symptoms are worsening, or are not improving after two weeks.
Children
Head injuries in children are common, usually minor, and harder to assess because they cannot describe what they feel.
Extra red flags in a child, alongside all of the above:
- Any head injury in a baby under 1, which needs assessment regardless.
- A soft spot that is bulging in a baby.
- Persistent crying, unusual irritability, or being inconsolable.
- Not feeding, or refusing to feed.
- Unusual floppiness or drowsiness.
- Not behaving like themselves, which a parent will notice long before any formal sign appears.
A parent's sense that something is wrong is a valid clinical signal and is treated as one. If you think your child is not right after a bang on the head, act on it.
Falls from a height greater than the child's own height, from a changing table, out of a cot, or down stairs, all warrant a lower threshold for seeking help.