Table 2 Clinical features warning of a possible underlying disorder

• Headache that peaks in severity in less than five minutes

• New headache type versus a worsening of a previous headache

• Change in previously stable headache pattern (e.g. progressive headache, worsening over weeks or longer)

• Headache that changes with posture (e.g. standing up)

• Headache awakening the patient

• Headache precipitated by physical activity or Valsalva manoeuvre (e.g. coughing, laughing, straining)

• First onset ≥50 years of age

• Focal neurological symptoms or signs

• Trauma

• Fever

• Seizures

• History of malignancy

• History of HIV or active infections