Headache is a symptom commonly encountered in everyday clinical practice, and, according to the WHO, one of the ten most common causes of functional disability. It may be primary (e.g., tension-type headaches, migraine) or secondary (e.g., following head trauma or infections) in nature. Although most episodes of headache are harmless, potentially life-threatening causes (e.g., subarachnoid hemorrhage, meningitis) should always be considered. Identifying the cause of headaches is often difficult and requires a detailed clinical history as well as a thorough physical examination. Additional diagnostics, e.g., imaging, are only indicated if headaches persist despite treatment or if specific clinical features are present that are signs of an underlying disease. This article gives an overview of the most common types of headache and serves as a guide to diagnosing different headache disorders.
Approach to management
- Check vital signs.
- Perform focused history and examination.
- If red flags are present:
- If no red flags are present and suspicion for life-threatening causes is low:
- Perform a detailed history and clinical exam.
- Consider whether further diagnostic testing is necessary.
- Provide supportive care.
- Identify and treat the underlying cause.
Headache red flags (SNOOP10) 
The original mnemonic, SNOOP has more recently been expanded to cover the following total of 15 red flags:
- Systemic symptoms (e.g., fever, signs of meningitis, myalgia, malaise)
- Neoplasm in history
- Neurological deficits/dysfunction (e.g., altered mental status, seizures) 
- Onset of headache is sudden or abrupt
- Older age at onset (> 50 years)
- Pattern changes of headache or recent onset
- Positional headache
- Precipitated by sneezing, coughing, or exercise
- Papilledema and other signs of increased ICP
- Progressive headache and atypical features
- Pregnancy or postpartum period
- Pain of the eye with autonomic features and visual deficits
- Posttraumatic onset
- Pathology of the immune system (especially due to HIV)
- Painkiller overuse or new drug at onset of headache
Life-threatening conditions 
- Intracranial hemorrhage: subarachnoid hemorrhage, epidural hemorrhage, intracerebral hemorrhage
- CNS infection: meningitis, encephalitis, brain abscess, subdural empyema
- Conditions causing increased ICP (e.g., intracranial neoplasm, brain abscess, ICH)
- Hypertensive emergency
- Internal carotid artery dissection
- Vertebral artery dissection
- Ischemic stroke
- Pituitary apoplexy
- Carbon monoxide poisoning
- Cerebral venous sinus thrombosis
- Preeclampsia or eclampsia
- Non-life-threatening conditions requiring urgent attention:
- Headache is a pain related to irritation and/or inflammation of intracranial or extracranial structures with pain receptors (e.g., meninges, cranial nerves, blood vessels).
- Primary headache: a headache that is not caused by another underlying condition 
- Secondary headache: a headache that is caused by another underlying condition (e.g., trauma, space-occupying lesion) 
- Lifetime prevalence: > 90%, with female predominance (except cluster headache) 
Most common forms of headache 
- Tension-type headache: 40–80% of cases
- Migraine: 10% of cases
Among patients presenting to the emergency department with headaches, primary headache (most frequently migraine) is the most common type, but up to 5% may have a secondary headache with a serious life-threatening cause. 
Epidemiological data refers to the US, unless otherwise specified.
See “Differential diagnoses” below.
- Duration of a single episode
- Clinical course (e.g., chronic, acute)
Nature of the headache
- Radiation of pain
- Severity (e.g., impact on patient's life)
- Triggers and exacerbating factors
- Associated symptoms
- Past medical history (e.g., hypertension, hypothyroidism, seizures, migraine, infections)
- Medications (e.g., anticoagulants , analgesics, OCPs)
- Caffeine intake
- Substance use
- Alcohol consumption
- Family history
- Blood pressure
- Presence of fever
- Signs of trauma
- Auscultation for bruits
- Palpation of pericranial muscles
- Palpation of the temporal artery; and assessment of jaw movement
- Palpation along the course of the trigeminal nerve branches
- Examination of the teeth and oral cavity
- Examination of the eye
- Examination of ocular movements
- Assessment of cervical spine mobility
- Palpation of the sinuses
- for neurological deficits
- Signs of
- Abdomen: inspection and palpation of the abdomen
- Skin: : Evaluate for rash or signs of drug use.
Consider secondary life-threatening causes if red flags for headache are present!
- Check vital signs, obtain a history, and perform a physical and neurological examination.
- Determine the need for further testing based on risk stratification and the suspected diagnosis.
- Low-risk headache: No routine laboratory tests or imaging are recommended.
- High-risk headache: Consider diagnostic workup based on the suspected diagnosis.
In patients who are unstable or have signs of increased ICP, diagnostics should not delay stabilization (e.g., ) and .
The diagnostic modality should be determined by the patient history and clinical presentation. Primary headache is a clinical diagnosis and typically does not require laboratory or imaging evaluation.
Risk stratification of headache 
- There are no routine recommended laboratory studies for headaches. Consider the following based on clinical suspicion:
- For emergency neuroimaging
- For urgent (arranged prior to discharge) neuroimaging in the emergency department:
- Patients > 50 years of age with a new type of headache but normal neurological examination
- In all other situations, imaging should be considered based on the suspected diagnosis and risk stratification.
- Test of choice
- The initial test of choice is usually a head CT without contrast.
- See the table below for other imaging modalities to consider.
|Recommended initial imaging modality for headache |
|Initial test of choice||Alternatives|
|Sudden-onset severe headache (i.e., thunderclap headache)|| || |
|New headache with papilledema|| || |
|New or worsening headache related to head trauma or accompanied by red flags|| || |
(e.g., cluster headache)
| || |
|Chronic headache with new features or change in character, severity, or frequency|| || |
In patients presenting to the emergency department with acute headache and a normal neurological examination, a negative head CT without contrast indicates that the diagnosis of SAH is unlikely, even when performed < 6 hours from the onset of headache (see “Diagnostics” in “Subarachnoid hemorrhage.”) 
Additional diagnostics to consider 
- Lumbar puncture (LP) with CSF analysis: for suspected meningitis, suspected inflammatory process or malignancy, or if there is a high suspicion of SAH without proof on CT scan
- Tonometry: if increased intraocular pressure is suspected
- EEG: for any form of suspected seizures or complex migraine
- Temporal artery biopsy: if GCA is suspected
In the emergency department, if SAH is still suspected despite a normal head CT without contrast, either LP or CTA can be used as a second-line test to safely rule out the diagnosis (see “Diagnostics” in “Subarachnoid hemorrhage”). 
|Types of primary headaches |
|Characteristics||Tension-type headache||Migraine headache||Cluster headache|| |
Mixed type headache 
|Clinical features||Attack duration|| || || || |
|Frequency|| || || |
|Localization|| || || || |
|Character|| || || |
|Intensity|| || || || |
| || || |
“POUND:“ pulsatile, one-day duration, unilateral, nausea, and disabling intensity are the typical features of migraine headache.
|Diagnosis||Clinical features||Diagnostic findings||Acute management|
|Intracerebral hemorrhage |
|Subarachnoid hemorrhage |
|Subdural hematoma (SDH)|| |
|Epidural hematoma || |
|Cerebral venous sinus thrombosis || |
|Hypertensive crises |
|Ischemic stroke |
|Intracranial space-occupying lesions (e.g., ) |
|Concussion (e.g., mild traumatic brain injury) || |
| Acute angle-closure glaucoma |
|Trigeminal neuralgia || |
|Medication overuse headache|| |
- Trigeminal autonomic cephalalgias: , paroxysmal hemicrania, hemicrania continua
- Other primary headaches: cough headaches, headaches due to physical exertion, postcoital headache, primary stabbing headache
- ; ()
The differential diagnoses listed here are not exhaustive.
Indications for hospitalization
- Life-threatening secondary headache requiring inpatient management
- Suspected nonbenign secondary cause of headache that requires further investigation
- Intractable pain or inability to tolerate oral nutrition or hydration
- Medication overuse headache requiring supervised withdrawal (see “Disposition and referrals” in “Medication overuse headache”)
Discharge from the emergency department
Discharge home is appropriate once life-threatening causes of headache have been ruled out and the patient's symptoms improve with initial treatment (even if the headache is not completely resolved). 
- Consider appropriate prescription of analgesics and preventive medication based on the underlying diagnosis.
- Provide patient counseling and education.
- Ensure outpatient primary care follow-up, especially for patients at high risk of early recurrence. 
- Consider referral to neurology or a specialized headache clinic.
Appropriate discharge planning is important to ensure ongoing care and reduce unnecessary return visits to the emergency department e.g., due to recurrent headaches or incomplete treatment.