Assessment of headaches:
Summary points from NICE are(1):
Evaluate people who present with headache and any of the following features, and consider the need for further investigations and/or referral:
- worsening headache with fever
 - sudden-onset headache reaching maximum intensity within 5 minutes
 - new-onset neurological deficit
 - new-onset cognitive dysfunction
 - change in personality
 - impaired level of consciousness
 - recent (typically within the past 3 months) head trauma
 - headache triggered by cough, valsalva (trying to breathe out with nose and mouth blocked) or sneeze
 - headache triggered by exercise
 - orthostatic headache (headache that changes with posture)
 - symptoms suggestive of giant cell arteritis
 - symptoms and signs of acute narrow-angle glaucoma
 - a substantial change in the characteristics of their headache
 
Consider further investigations and/or referral for people who present with new-onset headache and any of the following:
- compromised immunity, caused, for example, by HIV or immunosuppressive drugs
 - age under 20 years and a history of malignancy
 - a history of malignancy known to metastasise to the brain
 - vomiting without other obvious cause
 
The two week referral criteria for a suspected brain tumour is linked below.
Do not refer people diagnosed with tension-type headache, migraine, cluster headache or medication overuse headache for neuroimaging solely for reassurance.
Consider using a headache diary to aid the diagnosis of primary headaches
If a headache diary is used, ask the person to record the following for a minimum of 8 weeks:
- frequency, duration and severity of headaches
 - any associated symptoms
 - all prescribed and over the counter medications taken to relieve headaches
 - possible precipitants
 - if female and of having periods - relationship of headaches to menstruation
 
Reference:
- NICE (November 2015). Headaches - Diagnosis and management of headaches in young people and adults