A thunderclap headache—which can extend well beyond just a few hours—could signal a serious condition and, as our authors notes, should prompt you to seek medical attention.

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Some headaches come on gradually—the average tension headache, for example. Others—like ice pick headaches—are sudden and swift. A thunderclap headache can develop just as quickly as an ice pick headache, but—unlike ice pick headaches, which typically don’t last longer than 10 seconds—a thunderclap headache can continue for as long as a week.

The pain of a thunderclap headache can radiate to your neck and upper back, and you also may experience nausea and vomiting (as with migraine symptoms)—and even loss of consciousness. In a 2014 study, the latter symptom, along with being age 50 or older, increased the risk of death associated with a thunderclap headache.

What Is a Thunderclap Headache?

A thunderclap headache can red-flag a potentially dangerous condition you may not be aware of until the headache strikes. Conditions that can underlie a thunderclap headache include:

• Bleeding in the brain due to a ruptured blood vessel
• A subarachnoid hemorrhage (bleeding in the space between the arachnoid membrane and the pia mater, which are two of the three membranes that encase the brain)
• Cervical artery dissection (a tear in the lining of the carotid artery, which supplies blood to the brain)
• Hypertensive crisis (dangerously high blood pressure)
• A brain tumor
• A blood clot in the brain
• An infection such as meningitis (this is rare)

Seek Medical Help for a Thunderclap Headache

It is vital to seek emergency medical attention if you develop a sudden, severe pain in your head that may be a thunderclap headache.

Speaking on the University of Utah Health Sciences Radio, Troy Madsen, MD, an emergency physician at University of Utah Healthcare, said that his biggest concern with a thunderclap headache is subarachnoid hemorrhage.

“Maybe 1 to 2 percent of the population, of all of us, just have possibly little brain aneurisms, just something we have and we may not know it,” Dr. Madsen commented. “But these individuals that have severe, sudden headaches like this, the big thing I’m worried about is something rupturing with that aneurysm, bleeding out, and that’s what’s causing the severe headache.”

But, Dr. Madsen added, this type of medical event is rare. “When studies have looked at it, they’ve found that about 10 percent of people who describe these thunderclap headaches, these very severe, sudden headaches, do end up having some sort of bleeding in the brain,” he said. “That means the other 90 percent just had it. For whatever reason, it just came on.

“The big thing I’m thinking about in the ER,” he continues, “is ruling out the bad stuff. Oftentimes, that means getting a CT scan of the head to look for any sign of bleeding there, making sure there’s no sign of that, and we may have to do some additional tests as well.”

Tests for Assessing Thunderclap Headache Symptoms

Medical tests such as a computed tomography (CT) scan, and magnetic resonance angiography (MRA) can be used to evaluate a thunderclap headache—a CT scan is effective at diagnosing subarachnoid hemorrhage, and MRA can be used to check for cervical artery dissection.

If these tests are inconclusive, you may be given a spinal tap (a procedure in which a sample of cerebrospinal fluid is taken for testing) if other symptoms suggest that your thunderclap headache may be due to meningitis.

Your doctor will treat your thunderclap headache by addressing the underlying cause. Treatment may require surgery.

Originally published in 2017, this post is regularly updated.