Overview of Primary Thunderclap Headache

Imagine you witness the sudden, loud bang of a significant car crash. Now imagine this car explosion is occurring in your brain.

This may be analogous to a primary thunderclap headache—a headache disorder that causes a sudden, extraordinarily severe and explosive onset of head pain.

It's important to note that this headache can mimic the same type of pain that accompanies life-threatening brain disorders—so, if a person has a thunderclap headache, they need to seek emergency medical attention.

In fact, a thunderclap headache is actually more likely to be from a serious blood vessel problem in the brain (like a subarachnoid hemorrhage) or another organic brain problem, than this rare primary headache disorder.

Lightening over a train track
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The International Headache Society defines a primary thunderclap headache as a “high-intensity headache of abrupt onset mimicking that of a ruptured cerebral aneurysm, in the absence of any intracranial pathology."

Also, according to the IHS "evidence that thunderclap headache exists as a primary disorder is rare." This means that an extremely thorough workup needs to be done on a person with a thunderclap headache to make sure nothing more serious is going on.

In other words, primary thunderclap headache is a diagnosis of exclusion—everything else must be ruled out first.


According to the classification criteria of the third edition of the International Classification of Headache Disorder, symptoms of a primary thunderclap headache include:

  • Intensity: Severe, "worst headache of my life."
  • Onset: Sudden, reaching maximum intensity in < 1 minute
  • Duration: Lasts 5 or more minutes.

In addition to the above features, a primary thunderclap headache cannot be explained by another medical condition.


A thunderclap headache is an unusual cause of a primary headache and every means should be taken to rule out other more serious medical conditions. For instance, vascular or blood vessel disorders of the brain, like a subarachnoid hemorrhage, often cause a thunderclap headache—so it's imperative these life-threatening conditions are ruled out first.

A person with a thunderclap headache must have a lumbar puncture showing normal cerebrospinal fluid or ​CSF, as well as normal brain imaging, usually with a brain CT scan and/or brain magnetic resonance imaging (MRI). Usually, a magnetic resonance angiography (MRA), and/or venography (MRV) is done to further rule out any blood vessel problem in the brain. Sometimes a cerebral angiogram is performed.

Examples of headaches that may mimic primary thunderclap headache are:


The cause of a primary thunderclap headache is largely unknown. It may be related to a spasm of the blood vessels in the brain.


Treatment of a thunderclap headache depends on the origin. For instance, the treatment of a subarachnoid hemorrhage would involve emergent medical and/or neurosurgical interventions.

If medical emergencies have been ruled out, treatment for a primary thunderclap headache can be challenging. Individuals generally do not respond well to typical headache pain relievers.

One older study in Neurology showed that nimodipine, a calcium channel blocker, may provide headache resolution in people with primary thunderclap headache. But, the study was quite small—only 11 patients—and there was no control group, which suggests a possible placebo effect.

More research on this rare primary headache disorder would be useful.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Lu SR, Liao YC, Fuh JL, Lirng JF, Wang SJ. Nimodipine for treatment of primary thunderclap headache Neurology. 2004 Apr 27;62(8):1414-6.

  • Headache Classification Committee of the International Headache Society. "The International Classification of Headache Disorders: 3rd Edition (beta version)". Cephalalgia 2013;33(9):629-808.
  • Schwedt TJ & Dodick DW. (2014). Thunderclap headache. In: UpToDate, Swanson JW (Ed), UpToDate, Waltham, MA.

By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.