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Headache is a very common presenting complaint (the main problem that brings a patient to a clinician) that can be encountered in most healthcare settings. However, there is a wide range of different types of headache, and while some are chronic and benign, some are worrying and require emergency care. It is important therefore to be able to spot the red flags (warning features that suggest a serious cause) and so judge how serious a headache might be.
This article explains the red flags of headache. It then describes the main chronic headache disorders and the features that help tell them apart.
To figure out red flags in headaches, let’s first explore the potential causes for acute headaches. What is important to establish with headaches is whether they are primary (i.e. idiopathic, meaning no underlying cause is found) or secondary (i.e. there is an underlying condition causing it).
Some secondary headaches need rapid investigation and emergency assessment. One group is vascular conditions (conditions of the blood vessels). These include subarachnoid haemorrhage (bleeding into the space around the brain), cerebral venous thrombosis (a blood clot in the veins that drain blood from the brain) and giant cell arteritis (inflammation of the arteries of the head, which usually affects people over 50). Another group is infection or inflammation of the brain, such as meningitis, encephalitis (inflammation of the brain tissue) and brain abscess. Ophthalmic emergencies (eye emergencies), such as acute glaucoma (a sudden rise in pressure inside the eye), can also cause headache. So can systemic hypertension (high blood pressure), for example in pre-eclampsia (high blood pressure in pregnancy, with signs of organ damage).
Many of these pathologies can increase intracranial pressure (the pressure inside the skull). This can show as specific signs such as papilloedema (swelling of the optic disc, seen at the back of the eye).
A vascular cause such as a subarachnoid haemorrhage typically presents with a thunderclap headache. This is a headache that is sudden in onset and very intense, typically peaking within 5 minutes (classically within 1 minute). A thunderclap headache points towards a vascular cause and should be treated as an emergency.
Accompanying systemic symptoms (symptoms that affect the whole body, such as fever) could indicate infection, such as meningitis or encephalitis.
Neurological symptoms can point to a space-occupying lesion (a growth, such as a tumour, that takes up room inside the skull). Visual symptoms and eye pain may point towards acute glaucoma.
Any new-onset headache in patients over 50 years old should prompt assessment for a secondary headache. It may indicate giant cell arteritis or a space-occupying lesion.
The following mnemonic can be used to memorise the main red flags: SPOON. It stands for Systemic symptoms, Papilloedema, Onset new after the age of 50, Onset sudden (thunderclap) and Neurological symptoms. SPOON does not list every red flag. NICE guideline CG150 also lists new-onset cognitive dysfunction (problems with thinking and memory), change in personality, impaired level of consciousness, recent head trauma (typically within the past 3 months), headache triggered by coughing, sneezing or a Valsalva manoeuvre (trying to breathe out with the nose and mouth blocked), headache triggered by exercise, headache that changes with posture, symptoms suggestive of giant cell arteritis, symptoms and signs of acute narrow-angle glaucoma, and a substantial change in the characteristics of the headache.
Table - The red flag symptoms of headaches, and which emergency condition each symptom might indicate
For more details on the investigation, diagnosis, and management of some of these secondary headaches, refer to the specific articles.
Brain tumours are a concern for many patients presenting with chronic headaches. Before reassuring the patient, ask specific questions to help rule out a brain tumour. Ask about: signs of raised intracranial pressure; focal neurological signs (signs that point to one area of the brain, such as weakness on one side); more vague features such as personality change; and onset in patients over 50.
In adults, the most common brain tumours overall are secondary brain tumours, resulting from metastasis from other primary cancers. Tumours that commonly metastasise to the brain include lung, breast, colon, kidney and skin cancers.
Primary brain tumours arise in the brain or its associated structures. More than 12,000 people are diagnosed with a primary brain tumour each year in the UK, and about half of these tumours are cancerous (NHS: brain tumours).
Primary brain tumours may be non-cancerous or cancerous. Lower-grade tumours (grades 1 or 2) generally grow more slowly, while higher-grade tumours (grades 3 or 4) are generally more aggressive. Grade, tumour type and location all influence prognosis; a low-grade tumour can still cause serious problems.
There are many types of brain tumours, classified by their cellular and molecular features. The type matters because it influences prognosis and treatment. Gliomas are tumours of the glial cells, the supporting cells of the brain. Astrocytomas are gliomas that arise from astrocytes (star-shaped glial cells). The relative frequency of primary tumour types varies with age and the tumour categories included. Glioblastoma is an aggressive glioma. Modern classification distinguishes IDH-wildtype glioblastoma from IDH-mutant astrocytoma. IDH stands for isocitrate dehydrogenase, an enzyme. A tumour is IDH-mutant if the gene for this enzyme is altered, and IDH-wildtype if it is not. Other tumour types include vestibular schwannomas, ependymomas and neuronal tumours. Vestibular schwannomas arise from Schwann cells (the cells that wrap around nerves outside the brain and spinal cord). Ependymomas arise from ependymal cells (the cells that line the fluid spaces of the brain).
Migraine commonly presents as a unilateral headache, usually frontotemporal (felt over the forehead and the temple), although it is not always one-sided. The headache is often described as throbbing or pulsating. Episodes last from 4 to 72 hours. Migraine headaches are typically aggravated by light and noise, meaning patients may report photophobia (dislike of light) or phonophobia (dislike of noise), and prefer to be in a quiet, dark room. The headache is often accompanied by nausea (feeling sick) and sometimes vomiting. Many patients with migraine find that going to sleep can help relieve symptoms. Acute treatment is with medicines such as triptans (drugs that act on serotonin receptors to stop a migraine attack). NICE advises an oral triptan combined with an NSAID (non-steroidal anti-inflammatory drug, such as ibuprofen) or with paracetamol. People who prefer one drug can be offered a triptan, an NSAID, aspirin or paracetamol alone.
Some migraine episodes can be preceded by what is known as an ‘aura’. An aura is a temporary, fully reversible neurological symptom that usually comes before the headache. It develops gradually over at least 5 minutes and lasts 5 to 60 minutes. It can be visual (for example flashing lights), sensory (for example pins and needles or numbness) or a disturbance of speech. Some patients with migraine find that their aura is so characteristic that they can predict when the headache is coming. A triptan should be taken at the start of the headache, not at the start of the aura (unless the aura and headache start together).
The pathophysiology of migraine (how the condition develops in the body) is still unclear. However, some factors can trigger episodes, such as stress, lack of sleep, skipping meals, too much caffeine and periods (menstruation). Certain foods or drinks trigger attacks in some people, but craving a particular food can also be an early sign that an attack has started, so a food is not always the cause. Triggers differ between people, and a migraine diary can help to find them. Family history also seems to play a role in susceptibility. Migraine affects women more than men. Most patients who suffer from migraines will have had their first episode before their 30s and the severity of the episodes seems to decrease with age.
Tension headache is the most common type of headache and typically presents as a bilateral headache, with pain running from the forehead to the back of the head (the occiput). The pain often spreads into or arises from the neck. It is often described as a squeezing, band-like type of pain and non-pulsatile with a mild to moderate intensity. It is usually worse at the end of the day as it is aggravated by stress, sleep deprivation, and poor posture.
For tension-type headache, chronic is defined by frequency: headache on 15 or more days per month for more than three months. It is episodic if it occurs on fewer than 15 days per month. Tension-type headache affects women more than men and is less common in older age groups. Onset after 50 years of age is unusual and should prompt assessment for secondary causes. Mild nausea can occur in chronic tension-type headache, but episodic tension-type headache is not accompanied by nausea or vomiting. For acute attacks, NICE advises considering aspirin (not for under 16s), paracetamol or an NSAID, and not offering opioids (morphine-like painkillers). Frequent use of painkillers can cause medication overuse headache (see below). The exact mechanisms of tension-type headache are not known. Peripheral pain mechanisms (in the tissues around the skull) are most likely to play a role in episodic tension-type headache. Central pain mechanisms (in the brain and spinal cord) are more important in chronic tension-type headache. Increased tenderness of the muscles around the skull (pericranial tenderness) is the most significant abnormal finding.
Medication overuse headache paradoxically arises from taking acute headache medicines too often, such as analgesia (painkillers) or triptans, most commonly as a treatment of headaches. It often occurs alongside other conditions (co-morbidities) such as depression and insomnia (difficulty sleeping). It affects women more than men, and prevalence is highest in people aged 40 to 49 years.
Medication overuse headache is diagnosed when all of the following apply:
- The patient has a pre-existing headache disorder.
- Headache occurs on at least 15 days per month.
- The patient has regularly overused acute headache medication for more than 3 months.
- There is no better alternative diagnosis.
For paracetamol, aspirin and NSAIDs such as ibuprofen, overuse means use on at least 15 days per month. For opioids, triptans, ergots (ergotamine-type drugs) or combination analgesics (painkillers that contain two or more drugs, such as paracetamol with codeine), the threshold is at least 10 days per month. These patterns must continue for more than 3 months. Count days of use, rather than the number of doses taken on each day.
Management includes withdrawal of the overused medication and treatment of the underlying headache disorder. NICE advises stopping all overused acute headache medicines for at least 1 month, and stopping abruptly rather than gradually. Warn patients that the headache is likely to get worse in the short term before it improves, and that withdrawal symptoms can occur. Provide close follow-up and support, and review the diagnosis and progress 4 to 8 weeks after withdrawal starts. For people using strong opioids, consider specialist referral, and see NICE guidance on medicines associated with dependence or withdrawal symptoms.
Cluster headaches are an intense type of headache that is localised to the orbital area. Patients usually complain of pain around or behind the eye, and it may spread above the eye or along the side of the head. It is described as sharp and penetrating. This is a type of headache that is more common in men than women (about 3 to 1, although more women are now being diagnosed) and it most often starts between 20 and 40 years old. Onset of each attack is usually sudden. Untreated, each ‘attack’ lasts 15 to 180 minutes. Attacks can occur from once every other day to 8 times a day. A run of attacks is called a cluster or bout. Clusters usually last 2 weeks to 3 months, with remissions (symptom-free periods) of months to years between them. Cluster headache can also be episodic or chronic, but the terms are defined differently from tension-type headache. It is chronic if attacks continue for a year or longer without remission, or with remission periods lasting less than 3 months (the International Classification of Headache Disorders definition). NICE CG150 uses a shorter pain-free period: chronic cluster headache has a continuous pain-free period of less than 1 month in a 12-month period.
Attacks often start at night. For a diagnosis, the patient must also have either restlessness or agitation, or cranial autonomic features (signs from the autonomic nervous system, which controls involuntary body functions, on the same side as the pain). Autonomic features include red, watery eyes; ptosis (a drooping eyelid); a small, constricted pupil (miosis); a swollen eyelid; sweating of the forehead and face; and nasal congestion or a runny nose. During a cluster, attacks are also associated with a variety of triggers such as alcohol, histamine (a chemical released in allergic reactions), GTN (glyceryl trinitrate, a drug that widens blood vessels) spray, heat, exercise, sleep deprivation and inhalation of solvents. Other factors thought to increase susceptibility are head trauma, alcohol consumption and smoking. The pathophysiology of cluster headache is still not well understood. Acute attacks can be treated with high flow oxygen (100% oxygen at a flow rate of at least 12 litres per minute through a non-rebreathing mask with a reservoir bag). A subcutaneous (under the skin) or nasal triptan can be used instead of oxygen or as well. NICE advises against paracetamol, NSAIDs, opioids, ergots (drugs such as ergotamine, which come from the ergot fungus) and oral triptans for acute attacks. To prevent attacks during a bout, NICE advises considering verapamil (a calcium channel blocker, a drug that relaxes blood vessels). If you are unfamiliar with its use for cluster headache, seek specialist advice before starting it. That advice includes electrocardiogram (ECG) monitoring, which records the heart's electrical activity.
Trigeminal neuralgia (neuralgia means nerve pain) is a unilateral facial pain syndrome in the distribution of the trigeminal nerve (cranial nerve V). It usually affects the maxillary branch (which supplies the cheek and upper jaw) or the mandibular branch (which supplies the lower jaw), alone or together. The pain is therefore usually felt in the cheek, the jaw or the lower part of the face. Pain in the ophthalmic branch alone (which supplies the forehead and the area around the eye) is uncommon. The pain can radiate to the lips, nose, and scalp. It is described as sharp and stabbing in nature almost like an ‘electric shock’ and it is severe in intensity.
Trigeminal neuralgia affects women more than men and has an increased incidence with age. It usually starts between the ages of 50 and 60, and is rare in people younger than 40.
Episodes occur with a rapid onset and last for a few seconds to 2 minutes, stopping suddenly. Some triggers or factors that can make symptoms worse include eating, cold wind, vibration, or light touch to the face. Numbness or tingling found on examination (not just reported by the patient) is not typical of classical trigeminal neuralgia and, if present, should raise suspicion of a secondary cause. Classical trigeminal neuralgia is caused by compression of the trigeminal nerve, most commonly by a vascular loop (a blood vessel pressing on the nerve). Secondary trigeminal neuralgia is a consequence of major neurological disease, such as a tumour or multiple sclerosis (a condition that damages the nerve coverings in the brain and spinal cord). Carbamazepine (an antiepileptic drug) is the drug of choice. If carbamazepine cannot be used, does not work or is not tolerated, seek specialist advice. This can mean referral to a neurologist (a doctor who specialises in diseases of the nervous system) or a specialist in pain management.
There are many different types of headache, and management depends on the cause. It is therefore important to gather a comprehensive history from patients to help narrow the diagnosis.
For chronic headaches, management depends on the underlying type. Simple analgesia may help some patients, while triptans are used for acute migraine attacks, alongside consideration of preventive treatment (regular medicines that reduce how often attacks happen) where appropriate. Any suspected red flag headache needs urgent assessment, and may need emergency admission or urgent referral. Refer urgently if you suspect malignancy (cancer) or raised intracranial pressure, or if there are seizures, a change of personality, previous cancer or any unexplained focal deficits (signs that point to one area of the brain).
It can be helpful to ask patients to keep a headache diary for the more chronic presentations. A diary can help with the diagnosis of primary headaches (those with no underlying cause). NICE suggests recording the following for at least 8 weeks: how often the headaches happen, how long they last and how severe they are; any associated symptoms; all prescribed and over-the-counter medicines taken for the headaches; possible triggers; and how the headaches relate to menstruation (periods).
Imaging is not routine for headache. It is considered when red flags are present. NICE advises against imaging people with a diagnosed tension-type headache, migraine, cluster headache or medication overuse headache solely for reassurance. For a first bout of cluster headache, NICE advises discussing the need for neuroimaging with a GP with a special interest in headache or a neurologist. The choice of scan depends on the suspected cause. If review in secondary care by a senior clinician confirms an unexplained thunderclap headache or other signs that suggest subarachnoid haemorrhage, NICE advises an urgent non-contrast CT head scan (a CT scan done without an injected contrast dye). CT is most accurate within 6 hours of symptom onset. For other suspected causes, a CT or MRI scan is chosen as clinically indicated.
Edited by: Dr. Maddie Swannack
Reviewed by: Dr. Thomas Burnell and Dr. Marcus Judge
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