Severe Headache

When a severe headache is an emergency

Most severe headaches are not dangerous. Doctors use red flags, sometimes summarized as SNOOP, to spot the few that are:

• Systemic symptoms: fever, weight loss, cancer, HIV, pregnancy
• Neurological symptoms: confusion, weakness, vision loss, seizures
• Onset: sudden, thunderclap
• Older: new headache after age 50
• Pattern change, positional headache, or headache triggered by coughing, straining or exertion

A headache that peaks within a minute is a thunderclap headache and needs emergency assessment even if it starts to fade.

Common causes of a severe headache

Migraine

Migraine causes moderate to severe throbbing pain, often on one side, lasting 4 to 72 hours, with nausea, vomiting and sensitivity to light and sound. About a quarter of people have an aura beforehand, such as zigzag lights or tingling. Attacks are typically similar each time.

Cluster headache

Cluster headache is among the most painful conditions known: stabbing pain around one eye, lasting 15 minutes to 3 hours, with a red watery eye and runny nostril on the same side. Attacks occur up to several times a day for weeks, often at the same time each night. People pace rather than lie still.

Medication overuse headache

Taking pain relievers on many days a month can cause daily headaches that worsen. It is common in people with migraine.

Severe tension-type headache

Usually mild to moderate, but can be severe: a tight band around the head without nausea or throbbing.

Serious causes

Severe headache after a lumbar puncture or epidural

A post-dural puncture headache can develop after a spinal tap, spinal anesthetic or an epidural where the needle accidentally punctured the dura (the membrane around the spinal fluid). Spinal fluid leaks out, the brain sags slightly and pain-sensitive structures are stretched.

Typical features:

• starts within 1 to 3 days, sometimes up to 5 days
• severe pain at the front or back of the head, often spreading to the neck and shoulders
• much worse within minutes of sitting or standing, and eased within minutes of lying flat
• nausea, neck stiffness, ringing in the ears, muffled hearing or sensitivity to light

It happens more often with larger or cutting-type needles, in younger people and in women. See headache after lumbar puncture.

Treatment of post-dural puncture headache

• Conservative care: lie flat when the pain is bad, drink fluids, take acetaminophen (paracetamol) or ibuprofen as directed, and caffeine (from drinks or tablets, within safe limits). Many resolve within a week.
• Epidural blood patch: if the headache is severe or lasts more than 24 to 48 hours, an anesthesiologist injects a small amount of your own blood into the epidural space near the puncture site. It clots and seals the leak, and also raises pressure around the spinal fluid. Most people get significant relief within hours, and a second patch is occasionally needed.
• Red flags: a headache that stops being positional, or comes with fever, confusion, seizures or weakness, needs urgent review because rare complications such as a subdural hematoma or infection can occur.

How doctors evaluate a severe headache

The doctor will ask how fast it started, whether it is like previous headaches, what makes it better or worse (including position), and about fever, injury, pregnancy, medicines and blood thinners. The exam checks blood pressure, temperature, neck stiffness, eyes (including the optic nerves) and a full neurological exam.

Tests are used when a serious cause is suspected:

• CT scan of the head: within hours of a thunderclap headache it detects nearly all subarachnoid hemorrhages
• Lumbar puncture: for suspected meningitis or bleeding not shown on CT
• CT or MR angiography and venography: for aneurysms, artery tears and venous clots
• Blood tests: ESR and CRP for giant cell arteritis, blood count, and carbon monoxide levels
• Eye pressure if glaucoma is possible

Relief for a severe headache

• Migraine: take an NSAID such as ibuprofen or naproxen, or acetaminophen, early in the attack, following the label dose. Prescription triptans, gepants and anti-nausea medicines help more severe attacks. Rest in a dark, quiet room.
• Cluster headache: high-flow oxygen through a mask and injectable or nasal triptans work fastest. Over-the-counter tablets are too slow.
• Post-dural puncture headache: lie flat, fluids, caffeine and pain relief, then an epidural blood patch if needed.
• Avoid overuse: limit pain relievers to fewer than 10 to 15 days a month and see a doctor about prevention if you need more.

Do not give aspirin to children or teenagers. Avoid opioids for migraine, which are less effective and worsen rebound headaches.

Frequently asked questions

When is a severe headache an emergency?

A severe headache is an emergency if it peaks within a minute, comes with fever and stiff neck, causes confusion, weakness, speech or vision problems or a seizure, follows a head injury, or occurs in pregnancy or after birth. Call 911 or your local emergency number.

What causes a severe headache after a lumbar puncture?

It is usually caused by spinal fluid leaking through the small hole made by the needle, which lowers pressure around the brain. The headache is typically much worse when sitting or standing and eases when lying down. Most resolve within a week, and an epidural blood patch can seal the leak.

How does an epidural blood patch work?

A small amount of your own blood is drawn from your arm and injected into the epidural space near the original puncture. The blood forms a clot that seals the leak and raises the surrounding pressure. Most people feel better within hours, and the procedure is usually done as an outpatient.

What is the worst headache of your life a sign of?

A sudden, explosive "worst headache of my life" can be a sign of subarachnoid hemorrhage from a ruptured aneurysm, though other causes exist. It requires emergency evaluation with a CT scan and sometimes a lumbar puncture, even if the pain starts to ease.

How can I get rid of a severe headache fast?

For a known migraine, take your usual medicine early and rest in a dark, quiet room. Cluster headaches respond best to high-flow oxygen and injectable treatments. If the headache is new, sudden or comes with red flags, seek emergency care instead of treating it at home.