Head Injury: The Dangerous Signs

Key takeaways

The most dangerous thing about a head injury is that it arrives LATE. According to CDC, some signs show up immediately while others take hours or days to appear — so “they were walking and talking normally at the time” rules nothing out.
What needs doing after the blow is not only checking whether they are all right now, but having SOMEONE watch them over the hours that follow. According to NHS, an adult should stay with them for at least the first 24 hours.
Do NOT force the person to stay awake all night to keep watch. NHS says plainly that an injured person does not need to stay awake if they feel sleepy. What is worrying is not that they SLEEP, but that calling and shaking them does not wake them as it normally would.
Go to emergency care straight away if: a headache that keeps getting worse and will not go away · repeated vomiting · hard to rouse · loss of consciousness, even briefly · seizures · slurred speech, weakness or numbness · unequal pupils or double vision · clear fluid or blood coming from the ear or the nose.
According to NHS, there are situations that mean emergency care even with no signs yet: a fall from more than a metre or more than five stairs, the head struck at speed as in a road accident, a dent in the skull, or a baby under one year old with a bruise, swelling or large cut on the head.
Lower the threshold for being seen a great deal for anyone on blood-thinning medicine, anyone who had been drinking when they were injured, and young children. Do not stop an anticoagulant on your own — but the doctor must be told you are on one.

The most important thing first: after a bang to the head, “they seemed fine at the time” does not mean they are safe. According to CDC, some signs show up immediately while others take hours or days to appear. So what needs doing is to have someone watching over the hours that follow.

Recognising it: what counts as a head injury

According to CDC, a concussion — the medical name is mild traumatic brain injury — happens when the head is hit, bumped or jolted, or when the body is hit in a way that makes the head and brain move rapidly inside the skull: there does not have to be a direct blow to the head. CDC states plainly that doctors call this a “mild” injury because it is not usually life-threatening, but the effects can still be serious.

The common signs, according to CDC: headache; nausea or vomiting early on; dizziness, loss of balance; sensitivity to light or noise; blurred vision; exhaustion; difficulty concentrating, poor memory, a feeling of fog; irritability; sleeping more or less than usual.
A child too young to speak: fretting and crying more than usual, wanting more comforting, refusing the breast or eating poorly, not wanting to play, looking listless or unsteady on their feet.

According to CDC, the signs above are part of the normal process of healing — and the easy mistake is to take them as grounds for reassurance. Also, do not rely on the self-assessment of someone who has just been injured: CDC advises telling the family what signs to look out for — they may notice things before the patient does.

Why the dangerous signs arrive late

According to CDC, in a small number of cases a dangerous blood clot can form after a traumatic brain injury and crowd the brain against the skull. That is why someone who got up and walked away immediately after the blow still has to be watched: the thing that causes the danger needs time to grow.

What to do straight away

Write it down: what time the head was hit, where, how, whether there was any loss of consciousness, whether there was vomiting — these are exactly the markers the doctor asks about, and the ones most often misremembered.
Have someone with them: NHS says an adult should stay with the person for at least the first 24 hours — the person who will call for emergency help if the signs appear.
Genuine rest, avoiding stress; if they feel sleepy, let them sleep. CDC advises keeping to the usual bedtime and waking time.
For the swelling: NHS says to apply an ice pack wrapped in a towel, in short spells over the first few days.
For headache: NHS names paracetamol (acetaminophen) (there is a children's form); CDC advises asking the doctor which medicines are safe during recovery — how to use them is a decision for the doctor or the pharmacist.

What must NOT be done

Do NOT force them to stay awake all night to keep watch: NHS says an injured person does not need to stay awake if they feel sleepy. What has to be worried about is not that they SLEEP, but that calling and shaking them does not wake them as it normally would.
Do NOT drive yourself to emergency care after a bang to the head (NHS); and do not drive again until you have fully recovered.
Do NOT go back to sport or physical activity on the SAME DAY as the injury, and only go back when the doctor agrees (CDC); NHS says at least three weeks for contact sport — a second injury before the brain has healed can make recovery slower.
Do NOT drink alcohol until you are well again; and do not take sleeping tablets during recovery unless the doctor has prescribed them (NHS).
Do NOT apply leaf poultices or warming balms to the swelling: covering it over hides the very place that has to be watched.
Do NOT stop an anticoagulant or antiplatelet medicine the doctor has prescribed on your own — but do say immediately that you are taking one: that is the reason to go and be checked early.

When you must go to hospital

GO TO EMERGENCY CARE NOW, call 115 (the emergency number in Vietnam) or go to the nearest medical facility, if after the blow there is ANY of these signs. CDC: a headache that keeps getting worse and will not go away · repeated vomiting · drowsiness, hard to rouse, unable to open the eyes · loss of consciousness, even for a moment · slurred speech, weakness, numbness or limbs that have lost coordination · seizures · unequal pupils or double vision · confusion, restlessness, agitation, not recognising familiar people · a child too young to speak: crying that cannot be soothed, refusing the breast. NHS: clear fluid coming from the ear or the nose · bleeding from the ear, or bruising behind the ear · black rings around the eyes without a blow to the eyes · a wound with something embedded in it, or a dent in the skull. NHS: emergency care EVEN WITH no signs at all if the fall was from higher than a metre or more than five stairs · the head was struck at speed, as in a road accident · a baby under one year old has a bruise, swelling or a large cut on the head. — BE SEEN THE SAME DAY if none of the signs above is present but: the person is on blood-thinning medicine or has a bleeding disorder · they had been drinking alcohol or taking a stimulant at the time of the injury · they vomited once, or are dizzy · they are a young child · or you are worried.

A nosebleed after a blow to the head or face also means going now. A head injury has no safe waiting period: the blood clot CDC talks about does not keep to a timetable. NHS advises seeking medical advice for a child under five; according to CDC, older adults may recover more slowly.

Sources: the symptoms, the dangerous signs and the recovery guidance follow US CDC material on mild traumatic brain injury; the emergency markers based on how the injury happened, and the home care advice, follow NHS (UK) guidance. This article passes that on and does not replace being examined; citing CDC here does not imply that CDC endorses Y Te Xanh or our services.

A traumatic brain injury is something that has to be dealt with in hospital: brain imaging and monitoring on site exist only at a medical facility. If any sign in the box above is present, go in first and call afterwards. What we can do sits before and after that: a remote consultation so the family can decide whether to go in or keep watching; a doctor to the house to take the history, examine the patient and measure the vital signs; a nurse to provide care and monitoring at home during recovery.

Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.

Sources

CDC — About Mild TBI and Concussion
NHS — Head injury and concussion

Frequently asked questions

I banged my head but did not lose consciousness — do I still need to be seen?

Not losing consciousness does not mean there is no injury. According to CDC, a concussion happens when the head is hit, bumped or jolted, or when the body is hit in a way that makes the head and brain move rapidly back and forth — loss of consciousness is only one of the dangerous signs, not a condition for calling something an injury. NHS says most head injuries are not serious, but that you should seek medical help with any symptom. In practice: if any sign in the red-flag box is present, go to emergency care; if none is but you are in a higher-risk group — on blood-thinning medicine, having drunk alcohol when injured, a young child — be seen the same day; otherwise watch at home with someone present.

Do I have to wake someone who banged their head every hour to check on them?

No, and this is where many families do the opposite of what helps. NHS says plainly that an injured person does not need to stay awake if they feel sleepy; CDC goes further and advises keeping to the usual bedtime and waking time, sleeping in a dark room and cutting down on screens before bed — and lists sleeping more or less than usual among the common symptoms after a concussion. What has to be worried about is not that they SLEEP, but that they CANNOT BE WOKEN: increasing drowsiness, hard to rouse, unable to open the eyes. So what is needed is an adult staying with them who knows which signs mean calling for emergency help, not an alarm clock.

When does a child who has banged their head need to go to hospital?

According to NHS, a baby under one year old with a bruise, swelling or a large cut on the head belongs in the group that needs emergency care, along with all the general dangerous signs. NHS also advises calling a medical helpline for advice about a child under five. For a child too young to speak, CDC adds two dangerous signs the family can see: crying that cannot be soothed, and refusing the breast or not eating. Beyond that, watch for changes compared with that particular child when they are well: more fretful, wanting more comforting, a changed sleep pattern, not wanting to play, looking listless or more unsteady on their feet than usual.

What should I do if I bang my head while taking an anticoagulant?

Lower your threshold for being seen a great deal. NHS places people with a bleeding disorder or on blood-thinning medicine in the group that needs to seek medical advice after a head injury, even with no signs at all. Do not stop the medicine yourself, because it is preventing serious events; but do not wait and see either — go and be checked, and say clearly which medicine you take, bringing the packet with you. Adjusting the medicine is the job of the doctor who prescribed it, and they need to know this has happened. Remember to count antiplatelet medicines such as aspirin, and medicines prescribed long ago, not only something taken today.

How long can a headache after an injury last before I need to be seen again?

According to NHS, you may still have symptoms for up to about two weeks after a head injury, and you should see a doctor if symptoms last longer than two weeks. CDC likewise says most people feel better within about two weeks, and advises telling your doctor if you find you are not improving or your symptoms are getting worse. Keep a daily record of how things go so the doctor has real information. But do not confuse two different things: a persistent headache that is gradually easing is a matter for a follow-up appointment, whereas a headache that keeps getting worse and will not go away is a matter for emergency care.

How long after a head injury before I can drive and play sport again?

According to CDC, do not return to sport or physical activity on the same day as the injury, and ask your doctor for written guidance on when it is safe to return to work, school, sport and activities such as driving, cycling or operating heavy machinery. CDC also notes that a second injury before the brain has healed can make recovery slower or raise the risk of long-term effects, especially in teenagers and young adults. NHS says not to drive until you feel you have fully recovered, not to go back to work or school before you feel ready, and not to play contact sport for at least three weeks — children should avoid rough play for a few days.