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Lancaster University’s Laura White, Leon Gregary and Hedley Emsley look at why headaches send so many people to A&E – and what hospitals may be missing.
Every day, emergency departments see people whose headaches have become so severe, frightening or persistent that they feel they have no choice but to seek urgent medical help.
Headache is one of the most common reasons people attend A&E. While most headaches are not caused by serious disease, symptoms can sometimes mimic potentially life-threatening conditions such as brain haemorrhage, meningitis or stroke. Faced with sudden, severe or unusual pain, many people understandably worry that something serious is wrong.
For many patients, the cause is migraine, a neurological condition that can produce intense headache, nausea and sensitivity to light or sound. Others attend because a headache is lasting longer than expected, has become unusually severe, or feels different from anything they have experienced before. In some cases, the headache may simply become impossible to manage at home.
Medication-overuse headache
One particularly important but often overlooked cause is medication-overuse headache. This condition can develop when people frequently use medicines intended to treat headaches, including common painkillers and some migraine treatments.
It may sound surprising, but taking headache medication too often can sometimes cause headaches to become more frequent. Patients can become trapped in a cycle where recurring headaches lead to increasing medication use, which in turn contributes to further headaches. The worsening symptoms then prompt even greater reliance on medication.
Medication-overuse headache is thought to affect around 1% to 2% of the population. Yet many people have never heard of the condition. As a result, headaches may continue for months or even years before the underlying problem is recognised.
When people arrive in A&E with a headache, clinicians face an important challenge. Their first priority is to identify the small number of patients whose symptoms are caused by a serious underlying condition requiring urgent treatment. Most headaches will ultimately prove not to have a dangerous cause, but emergency clinicians must be alert for warning signs that could indicate bleeding, infection, raised pressure within the skull or other significant neurological problems.
This focus on identifying serious illness means emergency departments play a vital role in making headache care safe. But our research suggests that some of the detail about why patients attend with headache may disappear from routine hospital data.
As researchers working with routinely collected NHS data, we analysed 3,819 emergency department attendances for headache at a large acute NHS trust between 2021 and 2023. We expected to find a wide range of headache diagnoses. Instead, almost all patients were assigned one of just four diagnostic labels.
More than half were simply coded as “headache”, while just over 40% were coded as “migraine”. Together with trigeminal neuralgia and tension-type headache, these four labels accounted for almost 97% of all cases. Although 34 different diagnostic terms were technically available, the overwhelming majority of patients were grouped into a handful of broad categories.
We describe this phenomenon as “diagnostic compression”. While it may appear to be a technical issue, it matters because healthcare systems increasingly rely on coded data to understand patient needs, plan services and support research.
One finding stood out in particular. Medication-overuse headache was not recorded once in our dataset.
This does not necessarily mean the condition was absent. Given how common medication-overuse headache is in the general population, it seems likely that at least some patients attending emergency departments were affected. Yet if those diagnoses are not captured in routine data, it becomes difficult to understand how many people need support, how services should be organised, or whether opportunities for prevention are being missed.
Importantly, this is not a criticism of emergency clinicians. Emergency departments are designed to make rapid, safe decisions, often under considerable pressure. Recording highly specific headache diagnoses is rarely the immediate priority when the primary goal is to exclude serious illness and determine the next steps in care. Clinicians are also limited by the diagnostic coding systems available to them.
Better alignment is needed
The answer is unlikely to be asking busy staff to spend more time entering data. Instead, healthcare systems could do a better job of capturing a small number of clinically important details, such as whether a headache is new or longstanding, whether pain-relieving medicines are being used frequently, and whether recognised warning signs are present. Better alignment between headache classifications and routine coding systems could also help.
These changes may sound technical, but they could have real benefits for patients. If common headache disorders remain largely invisible in healthcare data, they risk being overlooked when services are designed or resources allocated. Understanding why people come to A&E with headaches is not only about identifying emergencies. It is also about recognising common conditions such as migraine and medication-overuse headache, and ensuring that patients receive the support they need before headaches become severe enough to send them to hospital.
Laura White is an NIHR academic clinical lecturer in neurology; Leon Gregary is an undergraduate medical student; Hedley Emsley is a consultant neurologist and professor of clinical neuroscience. This article is based on a service evaluation of emergency department headache coding undertaken at a large NHS trust.
