Headaches are common, but they do not all have the same cause. Some feel like a tight band around the head; others bring throbbing pain, nausea or sensitivity to light. Sleep changes, stress, dehydration and certain headache disorders can all play a part.
Most headaches are not a sign of a serious illness, but a sudden, extremely painful headache or a headache with certain neurological symptoms needs emergency assessment. This guide explains the science behind headache pain, common types and triggers, sensible self-care and when to seek medical attention in the UK.
Why Do We Get Headaches? Common Causes Explained
What actually causes headache pain?
A headache is pain felt in the head, face or upper neck. The brain processes pain signals, but the brain tissue itself is not sensitive to pain in the same way as skin and muscles. Instead, signals can originate from pain-sensitive tissues, blood vessels, nerves and membranes around the brain, as well as structures in the head and neck.
This is why headache pain can feel as though it comes from deep inside your head. But pain location does not necessarily identify the exact structure responsible, and the mechanisms behind migraine and other primary headache disorders are more complex than simple muscle tension or blood-vessel changes.
Clinicians distinguish between primary headaches—where the headache disorder itself is the condition—and secondary headaches, caused by another issue such as an infection, injury or another illness.
Three common headache types compared
| Type | Typical pattern | Other clues |
|---|---|---|
| Tension-type headache | Often a pressing or tightening sensation, commonly on both sides | Can be associated with neck or scalp tenderness; usually no prominent nausea |
| Migraine | Often throbbing and moderate to severe; may affect one or both sides | Nausea, sensitivity to light or sound, sometimes aura |
| Cluster headache | Extremely severe one-sided pain, often around an eye, in repeated attacks | Watery or red eye, nasal symptoms, restlessness or eyelid changes |
These are general patterns, not a self-diagnosis test. If your symptoms are new, unusual or severe, get appropriate medical advice.
1. What is a tension-type headache?
Tension-type headaches often feel like pressure or a tightening band around the head. They may affect both sides and can occur with tenderness in the neck, scalp or shoulders.
Stress, poor sleep and other factors can be associated with these headaches, although there may be no obvious trigger. One episode does not prove your headache is caused by stress or posture.
What may help: rest, water if you are thirsty or dehydrated, a regular sleep routine, and reducing prolonged neck or shoulder strain. If headaches keep returning or interfere with normal life, speak to a GP.
2. What is migraine?
Migraine is a neurological condition, not simply a particularly bad headache. An attack may include throbbing pain, feeling sick and sensitivity to light or sound. Pain is often worse with movement and may affect one side, but this is not universal.
Some people experience aura, such as zigzag lines, flashing lights, tingling or temporary speech difficulties. Others never have aura. According to the NHS migraine guidance, an attack may last from four hours to three days; aura symptoms lasting longer than an hour require urgent assessment.
Migraine may be influenced by family history, hormonal changes, stress, disrupted sleep, skipped meals and other individual factors. Not everyone has identifiable triggers.
What may help: resting in a quiet, dark room, drinking fluids, eating regularly and discussing appropriate treatment with a pharmacist or GP. The NHS advises against taking painkillers for headaches more than two days a week because frequent use can worsen headache problems.
3. What is a cluster headache?
Cluster headache is uncommon but can be extremely painful. It typically causes severe piercing or burning pain around one eye, often on the same side, and may occur repeatedly at similar times during a cluster period.
The NHS cluster headache guide describes attacks lasting 15 minutes to three hours, sometimes accompanied by a red or watering eye, a runny or blocked nostril, and marked restlessness. Specialist treatments are available; ordinary painkillers often do not help.
What to do: speak to a GP if you suspect cluster headaches. The NHS advises immediate emergency assessment for first-time eyelid drooping or a newly smaller pupil on one side, even in people already diagnosed with cluster headache.
Everyday factors that can contribute to headaches
Dehydration
Not drinking enough fluids—or losing them through sweating, vomiting or diarrhoea—can contribute to headaches. Other signs of dehydration can include thirst, dark urine or dizziness. Drink fluids regularly and replace losses appropriately; severe dehydration needs medical assessment.
Read our related guide to what happens when you do not drink enough water.
Disrupted or irregular sleep
Too little sleep, poor-quality sleep and significant changes in sleep timing are associated with headaches for some people. A regular sleep and wake schedule may help you recognise whether sleep is contributing. See Why Is Sleep Important? for an explanation of sleep’s role in health.
Stress and muscle tension
Stress can affect sleep, appetite and muscle tension and may contribute to headaches. Taking breaks and trying relaxation techniques can be useful, but persistent headaches should not automatically be dismissed as stress-related.
Skipped meals
Going long periods without eating can be a trigger for some people, including some with migraine. Keep a reasonably regular meal pattern and notice whether headaches coincide with missed meals.
Caffeine changes
Caffeine can affect headaches in different ways. Regular use followed by a sudden substantial reduction may produce withdrawal symptoms including headache. Too much caffeine can also interfere with sleep. If reducing a high intake, consider doing so gradually.
Alcohol
Alcohol can disturb sleep and contribute to dehydration and headache symptoms. The amount that affects a person varies, and not all headache attacks after drinking have exactly the same mechanism.
Screen use, eye strain and posture
Long periods at a computer can be associated with dry or strained eyes, poor ergonomics and muscle discomfort in the neck or shoulders. Take regular breaks, adjust screen position and consider an eye examination if reading or close work repeatedly leads to discomfort.
Colds, flu, sinus problems and other illness
Infections and some other health conditions can cause secondary headaches. Facial pressure and congestion can occur with sinus problems, but pain labelled a “sinus headache” may sometimes be migraine. Seek medical assessment for persistent, severe or unusual symptoms rather than assuming the cause.
Hormonal changes
Some people notice headaches around periods, pregnancy-related hormonal changes or menopause. Track the pattern and ask a clinician about options if attacks are troublesome. A severe or unusual headache during pregnancy or soon after giving birth needs medical advice promptly.
Why do headaches sometimes affect only one side?
Some headache disorders have characteristic patterns. Migraine often—but not always—affects one side. Cluster headache typically causes intense pain around one eye. Tension-type pain is frequently felt on both sides. Location alone cannot diagnose a headache, especially if it is new or unlike your usual pattern.
Similarly, throbbing pain and sensitivity to light or sound can suggest migraine, but they are not exclusive to it. Nausea, facial symptoms or other changes may provide useful context for a clinician.
How can you ease a mild headache safely?
If your headache is mild and you have no concerning symptoms, sensible first steps may include:
- Drink some water if you have not had enough fluids.
- Eat a normal meal if you have skipped one.
- Rest somewhere comfortable and reduce bright light if it bothers you.
- Take a break from screens and change position if you have been sitting for a long time.
- Try to maintain regular sleep, meals and caffeine habits.
- Ask a pharmacist about a suitable painkiller if needed, taking account of your age, health conditions, pregnancy status and other medicines.
Do not take more than the recommended dose or combine medicines without checking the label and professional guidance. If you are frequently reaching for painkillers, seek advice rather than repeatedly treating symptoms without a diagnosis.
Can painkillers themselves cause headaches?
Yes. Medication-overuse headache can develop when medicines for headache attacks are used too frequently over time. It can lead to an ongoing cycle of headache and more medicine use.
The relevant frequency varies by the type of medication, so there is no single safe threshold that applies to every product. The NHS migraine page advises trying not to take painkillers for headaches more than two days each week.
Discuss frequent medication use with a pharmacist or GP before making major changes to prescribed treatment, particularly if you rely on combination painkillers or other regularly taken medicines.
When is a headache an emergency in the UK?
The NHS distinguishes emergency symptoms from problems needing urgent but non-emergency advice. Call 999 or go to A&E now for a headache that starts suddenly and is extremely painful, or a headache with a seizure, weakness or numbness, difficulty speaking or walking, loss of vision, confusion, unusual drowsiness, or a very high temperature with signs such as a stiff neck or non-fading rash. A headache following a recent significant head injury also needs emergency assessment.
Do not drive yourself to A&E. Follow the NHS headaches emergency guidance.
Seek an urgent GP appointment or contact NHS 111 for a headache with vomiting, vision or eye problems, pain triggered or worsened by coughing or exertion, jaw pain while eating, a tender scalp, or other symptoms identified in the NHS guidance. For migraine, an attack lasting more than 72 hours or aura lasting more than one hour also warrants urgent advice. Pregnancy or having recently given birth can change the urgency of assessment.
Make a routine GP appointment for headaches that regularly recur, worsen over time, stop you doing everyday tasks or represent a significant change from your usual pattern. If you are unsure how urgently to seek help, NHS 111 can advise.
| Situation | What to do |
|---|---|
| Sudden, extremely severe headache; seizure; new weakness or speaking difficulty | 999 or A&E immediately |
| Headache with vomiting, concerning eye changes or worsening during coughing/exertion | Urgent GP assessment or NHS 111 |
| Repeated headaches affecting work, sleep or ordinary activities | Book a GP appointment |
| Occasional mild familiar headache without concerning symptoms | Consider self-care; ask a pharmacist if needed |
This table is a simplified guide. Always follow the full current NHS advice and seek emergency help when serious symptoms occur.
How to keep a useful headache diary
If headaches keep returning, a short diary can help identify patterns and provide information for a medical appointment. Record:
- Date, time and duration.
- Where the pain occurs and how severe it feels.
- Whether the pain is pressing, stabbing or throbbing.
- Associated symptoms such as nausea, visual changes or sensitivity to light.
- Sleep, meals, hydration, caffeine, alcohol and possible hormonal timing.
- Medicines taken, the dose and whether they helped.
- Whether the headache disrupted work, study or ordinary activities.
Do not feel you must find one trigger. Multiple factors may contribute, and some headaches occur without an obvious explanation. A diary is a tool for understanding patterns, not a substitute for assessment.
Frequently asked questions
Why do we get headaches if the brain itself cannot feel pain?
Pain-sensitive nerves and tissues around the brain and elsewhere in the head and neck send signals that the brain interprets as headache pain. Different headache disorders involve different mechanisms.
Can not drinking enough water cause a headache?
Yes. Dehydration can contribute, especially after fluid loss through heat, exercise or illness. Not every headache is caused by dehydration.
Why do I wake up with a headache?
Possible causes include disrupted sleep, migraine and other health conditions. Repeated morning headaches, particularly with snoring, gasping or marked daytime sleepiness, deserve GP advice.
Is a one-sided headache always migraine?
No. Migraine often causes one-sided pain, but other headache disorders can too. The associated symptoms and overall pattern matter.
Can stress cause headaches?
Stress may contribute through changes to sleep, muscle tension and daily habits. Frequent or unusual headaches still warrant appropriate assessment.
When should I worry about a headache?
A sudden extremely painful headache or one with serious neurological symptoms is an emergency. New, changing or recurrent headaches can also justify GP or NHS 111 advice depending on associated symptoms.
The bottom line
Headaches can come from pain-sensitive structures around the head and can have different causes, from everyday factors such as sleep disruption and dehydration to conditions such as migraine and cluster headache.
Pay attention to the pattern, severity and accompanying symptoms rather than assuming all headaches are alike. Self-care may help a familiar mild headache, but a sudden extremely severe headache or other red flags need prompt medical attention.
This article provides general educational information, not a diagnosis or personalised medical advice. NHS guidance: Headaches, Migraine and Cluster headaches.