There are numerous causes of headache, however, the pressing question in the ED is,

Is this a primary or SECONDARY headache?

  • Primary headaches [e.g. tension & migraine}, maybe painful and need analgesia but don’t require emergency investigation.
  • Secondary headaches, often but not always have serious underlying causes [e.g. SAH, central venous thrombosis] requiring emergent investigation and treatment

Red Flags [NICE] – serious secondary headaches

New severe or unexpected headache:

  • Sudden-onset severe headache reaching maximum intensity within 5 minutes may indicate serious causes such as intracranial haemorrhage, venous sinus thrombosis, hypertensive encephalopathy and vertebral artery dissection.
  • New onset headache in a person aged over 50 years may indicate a serious cause such as giant cell arteritis or space occupying lesion.

Progressive or persistent headache or headache that has changed dramatically:

  • Consider serious causes such as mass lesion or subdural haematoma

Associated features such as:

  • Fever, impaired consciousness, seizure, neck pain/stiffness or photophobia — consider serious causes such as meningitis and encephalitis.
  • Papilloedema — consider space occupying lesions, cerebral venous sinus thrombosis and benign intracranial hypertension.
  • New-onset neurological deficit, change in personality and new-onset cognitive dysfunction — consider serious causes such as a cerebrovascular event, malignancy or other space occupying lesions such as subacute or chronic subdural hematoma.
  • Atypical aura (duration greater than 1 hour, or including motor weakness) or aura occurring for the first time in a patient during use of combined oral contraceptives — consider serious causes such as cerebrovascular event.
  • Dizziness — consider serious causes such as ischaemic or haemorrhagic stroke.
  • Visual disturbance — can be associated with migraine but also with serious causes such as acute closure glaucoma and temporal arteritis.
  • Vomiting — can associated with migraine but may also be associated with a serious cause of headache such as mass lesion, brain abscess, or carbon monoxide poisoning.

Contacts with similar symptoms

  • Consider serious causes such as carbon monoxide poisoning if household contacts have similar symptoms.

Precipitating factors such as:

  • Preceding head trauma(usually within the past 3 months)  — consider serious causes such as subacute or chronic subdural hematoma.
  • Headache triggered by a Valsalva manoeuvre (such as coughing, sneezing, bending or exertion [physical or sexual]) — consider serious causes such as Chiari 1 malformation or a posterior fossa lesion.
  • Headache that worsens on standing — consider a CSF leak.
  • Headache that worsens on lying down — consider a space-occupying lesion or cerebral venous sinus thrombosis.

Comorbidities such as:

  • Compromised immunity (for example due to HIV or immunosuppressive drugs) — consider serious causes such as cerebral infection or malignancy.
  • Current or past malignancy — consider serious causes such as cerebral metastases.
  • Current or recent pregnancy — consider serious causes such as pre-eclampsia, central venous thrombosis.


What to do?

Due to the number and variety of diagnoses there is no one-size-fits-all plan. You must consider the likely diagnoses and tailor treatment and investigation. [senior involvement is often very helpful]


  • Not everyone with a red flag needs CT/MRI
  • Those that require CT/MRI some will need an emergent scan NOW and some potentially could wait for an urgent scan
  • If you feel they need CT discuss your differentials with radiology – as radiology are invaluable when deciding what is the most appropriate scan (e.g. SAH vs central venous thrombosis)


meningitis antibiotics

NICE – headache


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