Almost everyone gets headaches at some point. For many people, a headache is linked to stress, dehydration, tiredness, screen use, alcohol, hormones, poor sleep or a viral illness. Most headaches are not caused by anything dangerous and settle with rest, fluids, simple pain relief and time.
But headache is also one of those symptoms where context matters. A mild tension-type headache after a long day at work is very different from a sudden, explosive headache that reaches maximum intensity within seconds. A familiar migraine is different from a new headache in someone over 50, a headache with weakness down one side, or a headache with fever and a stiff neck.
This guide explains the common causes of headache, how to recognise different headache patterns, what “red flag” symptoms mean, when to call 999, when to use NHS 111 or see a GP, and what tests or treatments may be considered.
Important: this article is for general information only. It should not replace medical advice. If you are worried about a severe, unusual or worsening headache, seek medical help.
When a headache may be an emergency
Most headaches are not emergencies. However, some headache symptoms can point to serious conditions such as bleeding around the brain, stroke, meningitis, severe infection, raised pressure inside the skull, carbon monoxide poisoning or complications after a head injury.
Call 999 or go to A&E now if you have a headache with any of the following:
- a sudden, extremely severe headache, especially if it feels like the “worst headache of your life”
- a headache that reaches maximum intensity within seconds or minutes
- weakness, numbness, facial drooping, confusion, slurred speech or difficulty speaking
- new vision loss, double vision or severe eye pain
- a seizure or loss of consciousness
- a severe headache after a head injury, fall or accident
- fever, stiff neck, rash, confusion, drowsiness or dislike of bright light
- a headache with severe chest pain, breathlessness or symptoms of a stroke
- a severe headache during pregnancy or soon after giving birth
If you are unsure whether symptoms could be a stroke, it is safer to act quickly. You can read more in our guide to stroke symptoms and TIA. For official NHS advice on headaches, see the NHS headache guidance.
When to contact NHS 111 or arrange an urgent GP appointment
Some headaches are not 999 emergencies but still need prompt medical assessment. These include headaches that are new, changing, persistent or associated with symptoms that do not fit your usual pattern.
Contact NHS 111 or request an urgent GP appointment if:
- your headache is getting progressively worse over days or weeks
- your headache keeps waking you at night or is present on waking in the morning
- your headache is triggered or made worse by coughing, sneezing, bending, straining or exercise
- you have repeated vomiting with the headache
- you develop a new headache after age 50
- you have a new headache and cancer, HIV, a weakened immune system or recent serious infection
- you have headaches that are becoming more frequent or needing painkillers often
- you have a headache with jaw pain when chewing, scalp tenderness or visual symptoms, especially over age 50
- your headache feels different from your usual migraine or tension headache
NICE guidance on headache assessment highlights the importance of checking for red flags and recognising when a headache could have a secondary cause rather than being a primary headache disorder. You can read the professional guidance from NICE on headaches in people over 12.
Primary vs secondary headaches: what doctors mean
Doctors often divide headaches into two broad groups: primary headaches and secondary headaches.
A primary headache is a headache condition in itself. The headache is not caused by another disease that can be seen on a scan or blood test. Migraine, tension-type headache and cluster headache are the main examples.
A secondary headache is caused by something else. That “something else” may be simple, such as dehydration, sinus congestion, alcohol or medication overuse. But it can also be serious, such as meningitis, stroke, bleeding, raised intracranial pressure, temporal arteritis or a complication of high blood pressure.
The key question is not simply “how bad is the pain?” Some migraines are extremely painful but not dangerous. Some serious headaches may start subtly and become more worrying because of the pattern, timing, associated symptoms or medical background.
Common causes of headache
1. Tension-type headache
Tension-type headache is one of the most common headache patterns. It often feels like a tight band, pressure or dull ache around the forehead, temples, scalp or back of the head. It may affect both sides and can be linked with stress, poor sleep, long hours at a desk, jaw clenching, neck tension or dehydration.
Unlike migraine, tension-type headache usually does not cause severe nausea, vomiting or marked sensitivity to light and sound. Many people can continue normal activities, although they may feel uncomfortable or tired.
Helpful steps may include drinking water, eating if you have skipped meals, taking screen breaks, improving posture, stretching the neck and shoulders, getting sleep, and using simple pain relief when appropriate. If tension-type headaches become frequent, it is worth looking at sleep, stress, caffeine, workstation setup, eyesight, jaw clenching and how often painkillers are being used.
2. Migraine
Migraine is more than “just a bad headache”. It is a neurological condition that can cause episodes of moderate to severe head pain, often with nausea, sensitivity to light, sensitivity to sound, dizziness, fatigue and difficulty concentrating. The pain may be throbbing or pulsating and is often worse with movement.
Some people get migraine with aura. Aura can include visual symptoms such as flashing lights, zig-zag lines or blind spots. It may also involve tingling, numbness or temporary speech disturbance. Aura symptoms can be frightening, especially the first time they happen, and they can sometimes resemble stroke symptoms. If you have new neurological symptoms, especially weakness, facial drooping or speech problems, seek urgent medical help.
Migraine attacks can be triggered by many things, including lack of sleep, stress, dehydration, missed meals, alcohol, hormonal changes, bright light, certain foods, weather changes or too much caffeine. However, triggers vary between people, and not everyone can identify a clear cause.
For NHS information about migraine symptoms and treatment, see the NHS migraine guide. If you have chest tightness, palpitations or neurological symptoms alongside headache, you may also find our guides to chest pain and heart palpitations useful.
3. Cluster headache
Cluster headache is less common than migraine but can be extremely painful. It usually causes severe pain around one eye or one side of the head. Attacks may come in clusters over several weeks, often at a similar time each day or night.
Cluster headache may also cause symptoms on the same side as the pain, such as a red or watery eye, blocked or runny nose, eyelid swelling, facial sweating, a drooping eyelid or a smaller pupil. People often feel restless or agitated during an attack rather than wanting to lie still.
Because cluster headache can be very severe and has specific treatment options, recurrent one-sided attacks should be assessed by a GP or specialist.
4. Sinus-related headache
Sinus problems can cause pressure or pain around the forehead, cheeks, nose and eyes, especially during or after a cold. The pain may feel worse when bending forward. There may be a blocked nose, thick nasal discharge, reduced sense of smell, fever or facial tenderness.
However, many people who think they have “sinus headaches” actually have migraine. Migraine can cause facial pressure, blocked nose, watery eyes and sensitivity to light, so the two can be confused.
If you often get facial pressure, nasal symptoms or pain around the eyes, our guides to sinusitis, chronic sinusitis and hay fever may help you understand the pattern.
5. Dehydration, heat and missed meals
Headache is common when the body is short of fluid, salt, food or sleep. Dehydration headaches may come with thirst, dry mouth, dark urine, dizziness, fatigue or feeling light-headed when standing.
This is especially relevant during hot weather, after exercise, after vomiting or diarrhoea, or after drinking alcohol. You can read more in our guides to dehydration symptoms and heat exhaustion and heatstroke.
6. Medication-overuse headache
Medication-overuse headache can happen when painkillers or migraine medicines are used too often. This can create a cycle where the headache returns as the medicine wears off, leading to more painkiller use and more frequent headaches.
This does not mean painkillers are “bad”. Used occasionally and correctly, they can be very helpful. The problem is regular use over time, especially if you are taking painkillers on many days each month. If you feel you need pain relief frequently, speak to a pharmacist or GP rather than simply increasing the dose or taking tablets for longer.
7. Eye strain and vision problems
Uncorrected vision problems, long screen use, dry eyes and eye strain can contribute to headaches, especially around the forehead or eyes. Headaches from eye strain often build during the day and may be worse after reading, computer work or driving.
However, severe eye pain, a red eye, sudden blurred vision, halos around lights, nausea or vomiting can suggest a more urgent eye problem and should be assessed quickly. If you have ongoing eye symptoms, our eye health section includes guides to glaucoma, dry eye syndrome and cataracts.
8. High blood pressure
Most people with high blood pressure do not feel symptoms, which is why it is often called a silent condition. Mild or moderate high blood pressure is not usually the cause of everyday headaches. However, very high blood pressure, especially with chest pain, breathlessness, confusion, visual symptoms or neurological symptoms, can be serious and needs urgent medical assessment.
If you are concerned about your blood pressure, see our guides to high blood pressure and home blood pressure monitoring.
9. Hormonal headaches
Some people notice headaches or migraines around their period, during perimenopause, in pregnancy, after starting or stopping hormonal contraception, or when using HRT. Oestrogen changes can influence migraine in some people.
If headaches are linked to your cycle, it can help to keep a diary of headache days, period dates, sleep, stress, food, alcohol and medication use. This can make patterns easier to spot and can help a GP choose the most suitable treatment.
10. Stress, anxiety and poor sleep
Stress and anxiety can contribute to muscle tension, jaw clenching, poor sleep, changes in caffeine use and irregular meals — all of which can make headaches more likely. The headache is real; it is not “all in your head”. But the nervous system and body are closely connected, and stress can turn up the volume on pain.
If headaches come with panic symptoms, chest tightness, breathlessness or racing heart, it is important not to assume everything is anxiety until serious causes have been considered. You may find our guides to sertraline, mental health support options and sleep apnoea helpful depending on your symptoms.
Serious causes of headache to know about
It is not helpful to assume every headache is dangerous. But it is helpful to know the warning patterns that make clinicians think more carefully.
Thunderclap headache
A thunderclap headache is a sudden, severe headache that reaches maximum intensity very quickly. It may feel explosive or unlike anything you have experienced before. This pattern can be associated with bleeding around the brain, although there are other possible causes.
A thunderclap headache should be treated as an emergency. Call 999 or go to A&E.
Meningitis and sepsis
Meningitis can cause headache, fever, stiff neck, vomiting, dislike of bright lights, confusion, severe drowsiness, seizures or a rash that does not fade when pressed with a glass. Not everyone gets all symptoms, and symptoms can appear in any order.
For official information, see the NHS meningitis symptoms page. If meningitis or sepsis is possible, seek urgent medical help immediately.
Stroke or TIA
Headache can sometimes occur with stroke, especially when there are neurological symptoms such as facial drooping, arm weakness, speech problems, sudden confusion, visual loss, severe dizziness or loss of coordination.
If stroke symptoms are present, call 999. Do not wait to see if they pass.
Giant cell arteritis
Giant cell arteritis, also called temporal arteritis, is an inflammatory condition that usually affects people over 50. It can cause a new headache, scalp tenderness, pain when chewing, fatigue, fever, weight loss or visual symptoms. It matters because it can threaten eyesight if not treated quickly.
New headache after age 50 should be taken seriously, especially with jaw pain, scalp tenderness or changes in vision.
Raised pressure inside the skull
Raised intracranial pressure can cause headaches that are worse in the morning, worse when lying down, or worse with coughing, bending or straining. It may also cause vomiting, blurred vision, double vision, drowsiness or changes in behaviour.
This does not mean every morning headache is serious. Poor sleep, alcohol, dehydration, sleep apnoea and medication overuse can also cause morning headaches. But a new or worsening pattern should be assessed.
Carbon monoxide poisoning
Carbon monoxide poisoning can cause headache, dizziness, nausea, weakness, confusion and flu-like symptoms without a fever. It is especially suspicious if several people in the same home develop symptoms, symptoms improve when away from the property, or there is a faulty boiler, gas fire, stove or generator.
If carbon monoxide is possible, leave the property, get fresh air and seek urgent help.
How to understand your headache pattern
When assessing headache, clinicians usually ask about the story of the headache rather than just the pain score. The pattern often gives more useful information than one isolated symptom.
Useful questions include:
- When did it start?
- Did it come on suddenly or gradually?
- Where is the pain?
- Is it one-sided, both sides, behind the eye, at the back of the head or all over?
- What does it feel like — pressure, throbbing, stabbing, burning or electric shock-like?
- How long does it last?
- How often does it happen?
- Is this a familiar headache or a new type?
- Are there symptoms such as nausea, vomiting, fever, rash, stiff neck, weakness, numbness, visual changes or confusion?
- Is it linked to sleep, stress, periods, alcohol, caffeine, exercise, coughing, posture or screen use?
- What medicines have you taken, and how often?
A headache diary can be extremely useful. It does not need to be complicated. Note the date, time, duration, pain severity, possible triggers, associated symptoms, medicines taken and whether the medicine worked. Over a few weeks, patterns often become clearer.
What tests might be needed?
Many headaches can be diagnosed from the history and examination, especially if the pattern clearly fits migraine, tension-type headache or cluster headache and there are no red flags.
A clinician may check your blood pressure, temperature, eyes, neck movement, neurological function, jaw and scalp tenderness, sinuses, medication use and general health. Depending on symptoms, tests may include blood tests, eye assessment, CT scan, MRI scan or lumbar puncture.
Scans are not needed for every headache. In fact, scanning every person with a typical tension headache or familiar migraine can create unnecessary anxiety and incidental findings. But scans are important when the history or examination suggests a possible serious cause.
If you have been sent for investigations, our guides to understanding medical test results, blood test results and scan results may help you prepare.
What can help a headache at home?
If your headache is mild to moderate, familiar, and there are no red flag symptoms, simple self-care may help.
Start with the basics: drink water, eat something if you have missed a meal, rest in a quiet room, reduce screen brightness, avoid alcohol, and try gentle neck and shoulder relaxation. Some people find a cool compress helpful; others prefer warmth around the neck and shoulders.
Simple painkillers such as paracetamol or ibuprofen may help some headaches, but they are not suitable for everyone. Ibuprofen and other anti-inflammatory medicines may not be appropriate if you have a stomach ulcer, kidney disease, certain heart conditions, are on blood thinners, have severe asthma triggered by NSAIDs, or are pregnant unless advised by a clinician. Always follow the instructions on the packet or ask a pharmacist.
For migraine, taking treatment early in the attack often works better than waiting until the pain is severe. Some people need migraine-specific medicines such as triptans or anti-sickness medicines, which can be discussed with a GP or pharmacist.
When headaches keep coming back
Recurring headaches deserve a more strategic approach. Rather than treating each headache as a separate event, it is worth asking why they are happening so often.
Common reasons include poor sleep, stress, frequent painkiller use, migraine, caffeine fluctuation, dehydration, hormonal changes, untreated sleep apnoea, neck tension, eyesight problems, sinus disease or a long-term medical condition.
If headaches are affecting work, study, sleep, driving, parenting or quality of life, speak to a GP. Preventive migraine treatment, physiotherapy, sleep treatment, medication review, mental health support or further assessment may be appropriate depending on the pattern.
Headache in children
Children can get headaches for many of the same reasons as adults: viral illnesses, dehydration, lack of sleep, stress, eyesight problems, migraine or head injury. Younger children may not describe the pain clearly, so behaviour matters. A child who is unusually drowsy, confused, floppy, persistently vomiting, feverish with a rash, or has a stiff neck needs urgent medical attention.
Seek medical advice if a child has headaches that wake them at night, are present on waking, are getting worse, occur with vomiting, affect balance or vision, follow a head injury, or are associated with weakness, seizures or behavioural change.
Headache during pregnancy
Headaches can occur during pregnancy because of hormones, tiredness, dehydration, caffeine changes, sickness, stress or migraine. However, some headaches in pregnancy need urgent assessment, especially if they are severe, new, sudden, associated with visual symptoms, swelling, upper abdominal pain, high blood pressure or feeling very unwell.
If you are pregnant or recently gave birth and develop a severe or unusual headache, contact maternity triage, NHS 111, your GP or emergency services depending on severity.
How to prevent headaches
Prevention depends on the type of headache, but the foundations are often similar. Aim for regular sleep, regular meals, good hydration, sensible caffeine use, reduced alcohol, movement during the day, stress management and avoiding overuse of painkillers.
For desk-based work, check your screen height, chair position, lighting and whether you are clenching your jaw or raising your shoulders. For migraine, a diary may help identify triggers, but it is important not to over-restrict your life chasing every possible trigger. Often, migraine is less about one trigger and more about several factors adding up: poor sleep, stress, skipped meals and hormonal timing, for example.
If headaches are frequent, prevention may involve prescription medication, migraine-specific treatment, treating sleep apnoea, managing blood pressure, addressing anxiety, changing contraception, physiotherapy, or reducing medication overuse with support.
The bottom line
Most headaches are not dangerous, but some need urgent attention. The most important clues are the speed of onset, whether the headache is new or different, whether it is worsening, and whether there are symptoms such as weakness, confusion, fever, stiff neck, rash, visual loss, seizure, head injury or pregnancy-related warning signs.
If your headache is familiar and mild, self-care and pharmacy advice may be enough. If it is severe, sudden, unusual, progressive or associated with red flags, do not try to “sleep it off”. Seek medical help.
FAQ: Headache causes, red flags and urgent symptoms
What type of headache is most common?
Tension-type headache is one of the most common headache patterns. It often feels like pressure or tightness around the head, forehead, temples or neck. It is commonly linked with stress, poor sleep, dehydration, posture, screen use or muscle tension.
How do I know if my headache is serious?
A headache is more concerning if it is sudden and severe, different from your usual headaches, getting progressively worse, associated with neurological symptoms, follows a head injury, occurs with fever and stiff neck, or happens during pregnancy. If you are worried, seek medical advice.
What is a thunderclap headache?
A thunderclap headache is a sudden, very severe headache that reaches maximum intensity quickly, often within seconds or minutes. It can be a sign of bleeding around the brain or another serious condition. Call 999 or go to A&E if this happens.
Can migraine feel like a stroke?
Migraine aura can sometimes cause visual disturbance, tingling, numbness or speech symptoms, which can be frightening and may resemble stroke. If these symptoms are new, severe, prolonged, or include weakness, facial drooping or speech difficulty, seek urgent medical help.
Can high blood pressure cause headaches?
Most people with high blood pressure do not have symptoms. Everyday headaches are not usually caused by mildly raised blood pressure. However, very high blood pressure with symptoms such as chest pain, breathlessness, confusion, visual changes or neurological symptoms can be serious and needs urgent assessment.
Why do I wake up with a headache?
Morning headaches can be linked to poor sleep, dehydration, alcohol, caffeine withdrawal, teeth grinding, sleep apnoea, medication overuse or migraine. Less commonly, headaches that are worse on waking can be associated with raised pressure inside the skull. If morning headaches are new, worsening or associated with vomiting or visual symptoms, seek medical advice.
Can stress cause headaches every day?
Stress can contribute to frequent headaches through muscle tension, poor sleep, jaw clenching, irregular meals and increased sensitivity to pain. However, daily headaches should not automatically be dismissed as stress. A GP or pharmacist can help check for medication overuse, migraine, blood pressure problems, sleep issues and other causes.
How often is too often to take painkillers for headaches?
If you regularly need painkillers for headaches, especially on multiple days each week, ask a pharmacist or GP for advice. Frequent painkiller use can contribute to medication-overuse headache and may make headaches more persistent over time.
When should I see a GP about headaches?
See a GP if your headaches are recurrent, worsening, affecting daily life, changing pattern, not responding to usual treatment, or requiring frequent painkillers. You should also seek advice for a new headache after age 50 or headaches associated with visual symptoms, jaw pain, vomiting or neurological symptoms.
Can dehydration cause headaches?
Yes. Dehydration can cause headache, tiredness, dizziness, dark urine, dry mouth and feeling light-headed. It is more likely after hot weather, exercise, alcohol, vomiting, diarrhoea or not drinking enough fluids.
Are headaches behind the eyes usually sinus problems?
Not always. Pain behind or around the eyes can be caused by migraine, sinusitis, eye strain, dry eyes, cluster headache or, rarely, urgent eye conditions. Severe eye pain, red eye, sudden vision changes or halos around lights should be assessed quickly.
Should I get a brain scan for headaches?
Not every headache needs a scan. Many headaches can be diagnosed from the history and examination. A scan may be needed if there are red flags, abnormal neurological findings, a sudden severe headache, a new or worsening pattern, cancer history, immune suppression or other concerning features.
Can headaches be caused by caffeine?
Yes. Too much caffeine can trigger headaches in some people, while suddenly reducing caffeine can also cause withdrawal headaches. Keeping caffeine intake consistent and moderate may help if headaches are frequent.
What should I track in a headache diary?
Track the date, time, duration, pain location, severity, associated symptoms, possible triggers, sleep, meals, period dates if relevant, medication taken and whether it helped. A diary can help identify migraine, hormonal patterns, medication overuse or lifestyle triggers.
When is a headache with fever dangerous?
A headache with fever can happen with common viral infections, but it is more concerning if there is a stiff neck, rash, confusion, severe drowsiness, dislike of bright light, repeated vomiting or seizures. These symptoms can suggest meningitis or sepsis and need urgent medical help.
