- Sudden “thunderclap” headache reaching maximum severity in seconds is a medical emergency — go to A&E.
- Most chronic headaches are tension-type or migraine — uncomfortable, treatable, not dangerous.
- Red flags include: sudden severe onset, fever with neck stiffness, neurological symptoms, headache different from your usual pattern, new onset after age 50.
- Over-the-counter painkillers used more than 10–15 days per month can themselves cause chronic headache.
The good news first
Around 90–95% of recurring headaches are “primary” — tension-type, migraine, or cluster. They’re not caused by another disease and they’re not dangerous, even when severe. The unpleasant truth is also the reassuring one: most headaches are treatable but not sinister.
The small minority of headaches that are “secondary” — caused by something else, like infection, bleeding, or pressure inside the head — have specific warning features. Recognising these is what this article is about.
Go to A&E or call 999 if...
Any of these features with a headache warrant emergency care:
- Sudden severe headache reaching maximum intensity in seconds to a minute (“thunderclap”) — concerning for bleeding around the brain (subarachnoid haemorrhage)
- Headache with fever AND neck stiffness AND/OR rash — possible meningitis
- Headache with confusion, drowsiness, or seizures
- Headache with new weakness, numbness, speech difficulty, or visual loss — possible stroke or other neurological event
- Headache after a recent head injury, particularly if worsening
- Headache with severe vomiting that you can’t keep down
- Worst headache of your life if it’s clearly different from your usual pattern
Don’t wait. Don’t take painkillers and see if it goes. Get assessed.
See a doctor within 24–48 hours if...
- New persistent headache that’s different from your usual
- Headache worsening over days to weeks
- Headache worse in the morning, or waking you from sleep
- Headache worse with coughing, straining, lying down
- Headache with visual changes that don’t completely resolve
- New headache after age 50 — particularly if combined with scalp tenderness or jaw pain on chewing (could be giant cell arteritis — needs urgent treatment)
- Headache with weight loss, fevers, or night sweats
- Headache in someone with cancer, HIV, or immunosuppression
- Headache in pregnancy with high blood pressure or visual changes
- Headache that’s significantly affecting your function and not responding to usual treatments
Routine appointment if...
- You have recurring headaches that fit a usual pattern (migraine, tension)
- You want to discuss prevention strategies
- You’re taking painkillers more than 10–15 days per month
- Headaches are starting to affect work, relationships, or quality of life
- Existing migraine treatment isn’t working as well as it did
- You want investigation to be reassured
When it’s migraine
Migraine is the second most common headache type and the most disabling. Features:
- Unilateral (one side) more often than both, but can be either
- Throbbing or pulsating quality
- Moderate to severe intensity
- Worse with movement, sound, light
- Often associated with nausea or vomiting
- Duration 4–72 hours untreated
- Sometimes preceded by “aura” — visual disturbances, tingling, speech changes — lasting up to an hour
Triggers vary: hormonal cycles, sleep disturbance, certain foods, alcohol, stress, weather changes.
Treatment is in two strands: acute (treating attacks) and preventive (reducing frequency). Many effective options exist; we can discuss.
When it’s tension-type
The most common headache type. Features:
- Both sides of the head, often described as a tight band
- Mild to moderate intensity
- Not worsened by movement
- Not usually associated with nausea or significant light/sound sensitivity
- Duration minutes to days
Often related to posture, screen use, stress, dehydration, sleep. Responds to lifestyle changes and simple analgesics. Doesn’t usually need extensive investigation if pattern is typical.
When it’s cluster
Less common but distinctive:
- Severe one-sided pain, classically around or behind one eye
- Short duration (15 minutes to 3 hours)
- Occurs in “clusters” — multiple attacks daily for weeks or months, then periods of remission
- Associated with eye watering, nasal congestion on the same side, restlessness
- More common in men
Often misdiagnosed as migraine or sinusitis. Effective treatments exist but require specialist input.
Medication-overuse headache
Counter-intuitively, painkillers taken frequently for headache can cause more headache. Pattern:
- Taking simple analgesics (paracetamol, ibuprofen) more than 15 days a month
- Taking combination painkillers, opioids, or triptans more than 10 days a month
- Daily or near-daily headache that’s changed character
Treatment involves carefully reducing the medication, which initially worsens headache before improving. Worth seeking medical advice rather than doing alone.
Headache in children
Most children’s headaches are also primary (migraine, tension). Same red flag features apply. Particular concern with:
- Headache that wakes a child from sleep
- Persistent vomiting without obvious infection
- Personality or behaviour changes
- Worsening over weeks
- Co-ordination or vision problems
Children with new persistent or recurrent headaches should be assessed.
What helps day to day
For most chronic headache:
- Sleep regularity — consistent times, adequate hours
- Hydration — particularly with caffeine intake
- Identify and reduce triggers — keep a headache diary for 4 weeks
- Manage stress — specific strategies appropriate to your situation
- Posture and screen time — particularly for tension-type
- Limit analgesic use — below 10 days per month
- Regular exercise — reduces migraine frequency in many people
- Reduce alcohol
If headaches are frequent, severe, or changing, see a doctor for proper assessment. Many treatments exist that aren’t available over the counter.
Persistent or changing headaches warrant proper assessment. Book a 30-minute consultation and we’ll work through what’s going on and what to do about it.