A mild head injury is one of the more common reasons a patient walks into a community pharmacy the day after a bump, a fall, a football clash or a cycling spill. The presenting complaint is usually a headache, and the question is which painkiller is safe. The answer is not as simple as "ibuprofen works for most headaches" — after a head injury there is a narrow window where non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin are cautioned, paracetamol is the pharmacy default, and a specific set of red flags must be ruled out.
This article summarises NICE NG232 on head injury and NICE CKS guidance for pharmacy consultations on post-concussion headache, and explains why the standard analgesic hierarchy shifts after a knock to the head.
What "mild head injury" means
NICE NG232 defines head injury broadly as any trauma to the head, with or without loss of consciousness. "Mild" or "minor" in the clinical literature typically refers to a Glasgow Coma Scale of 13–15 at presentation, brief or no loss of consciousness, and no focal neurological signs.
A significant proportion of mild head injuries result in post-concussion symptoms: headache, dizziness, fatigue, cognitive slowing, nausea, sleep disturbance and photophobia. Most resolve within days to a few weeks without specific treatment. A small minority deteriorate because of delayed intracranial bleeding, which is the reason the pharmacy analgesic decision matters.
Paracetamol is the counter default
For post-concussion headache presenting to pharmacy in the days after a minor head injury, paracetamol at standard adult dose (up to 1 g four times daily, maximum 4 g per 24 hours) is the appropriate first-line option. Paracetamol does not affect platelet function, does not increase bleeding risk, and has a well-established safety profile.
The practical counter advice is:
- Standard dose, standard interval, no more than four doses in 24 hours.
- Avoid combination products (co-codamol, Sudafed PE combinations, Lemsip variants) that exceed the cumulative paracetamol dose when taken alongside a separate paracetamol purchase.
- Rest and hydration alongside analgesia.
- A quiet, dimly lit environment if photophobia or noise sensitivity is present.
Why NSAIDs and aspirin are cautioned
The reason ibuprofen, naproxen and aspirin are not straightforwardly recommended after a head injury is that they inhibit platelet function, which theoretically increases the risk of worsening an undetected intracranial bleed. NICE CKS on head injury advises avoiding NSAIDs and aspirin in the first 48 hours after a minor head injury where there is any uncertainty about intracranial pathology.
In practice this means:
- Within the first 48 hours of a minor head injury: paracetamol only, unless a clinician has assessed the patient and specifically sanctioned NSAIDs.
- After 48 hours with no progressive symptoms: a standard NSAID is usually reasonable if paracetamol alone is insufficient, but caution still applies in elderly patients, those on anticoagulants, and those with concerning symptoms.
- Patients on warfarin, a direct oral anticoagulant (DOAC), or antiplatelet therapy who sustain any head injury should be referred for clinical assessment regardless of the apparent severity. The bleeding risk is materially higher.
Red flags that require urgent assessment
NICE NG232 sets out the criteria for CT scan and urgent care after a head injury. Any of the following, after a knock to the head at any point in the preceding two weeks, warrant urgent medical assessment — NHS 111, urgent care, or A&E depending on severity:
- Loss of consciousness of any duration at the time of the injury.
- Witnessed seizure.
- Vomiting more than once since the injury.
- Amnesia (before or after the event) lasting more than five minutes.
- Severe or worsening headache not responsive to paracetamol.
- Drowsiness, confusion, difficulty waking.
- Slurred speech, double or blurred vision, weakness or numbness on one side.
- Clear fluid from the nose or ears.
- Any new bruising behind the ear ("Battle's sign") or around the eyes ("panda eyes").
- Age 65 or older, especially after a fall.
- Dangerous mechanism of injury: road traffic collision, fall from height, assault.
- Anticoagulant or antiplatelet therapy.
- Bleeding or clotting disorder.
- Any injury in a child under 1 year.
Pharmacists should have a low threshold for referral. The consequence of missing delayed intracranial bleeding is severe, and the analgesia question should not be the reason a worrying presentation is triaged to self-care.
When paracetamol isn't enough
Persistent post-concussion headache that is not controlled by paracetamol at standard dose, after the 48-hour window and in the absence of red flags, is typically managed by the GP. Options considered at that level include the appropriate use of NSAIDs (weighing bleeding risk against benefit), treatment of associated symptoms such as nausea or sleep disturbance, and referral to a specialist concussion or neurology service where symptoms persist beyond four weeks.
Medication-overuse headache is an important longer-term consideration: patients using regular analgesia for weeks on end for ongoing post-concussion symptoms can develop a rebound pattern. This is another reason to escalate care rather than indefinitely supply OTC analgesia.
Return-to-activity advice
The pharmacy consultation is also an opportunity to reinforce the standard return-to-activity advice for mild head injury:
- Rest for the first 24–48 hours.
- Gradual return to normal activity if symptoms allow.
- Avoid alcohol for 24 hours.
- No driving while symptomatic.
- In sport, follow the relevant graduated return-to-play protocol (for example, the Concussion in Sport Group's consensus or the individual sport's governing body guidance).
Caveats
This article summarises NICE NG232, NICE CKS and NHS patient information current to April 2026. It is not a substitute for clinical assessment. If there is any doubt about whether a head injury requires medical review, the safe default is to refer.
Sources
- NICE NG232 — Head injury: assessment and early management
- NICE Clinical Knowledge Summaries — Head injury
- NHS — Concussion patient information
- British National Formulary — ibuprofen, paracetamol
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