Extremely hot peppers don’t just blister your mouth and bum—they can also spark fiery havoc in your brain, according to a report published Monday in BMJ Case Reports.

An otherwise healthy 34-year-old man developed a blood-flow disorder in his brain and suffered several debilitating “thunderclap” headaches after entering a hot pepper eating contest, US doctors reported. The man had managed to get down a Carolina Reaper pepper, which in 2013 earned the title of the world’s hottest chili by Guinness World Records.

In 2013, the Carolina Reaper—a cross between Sweet Habanero and Naga Viper chilies—clocked in at 1,569,300 Scoville Heat Units (SHU), a unit of measure for a chili’s spiciness. For comparison, jalapeños fall in the range of 2,500 and 8,000 SHUs, while ghost peppers (Bhut Jolokia) register at just over 800,000. In 2017, the Carolina Reaper took the title again, with a pepper grown in South Carolina that measured 1,641,183 SHUs. (Though there have been reports of a “Pepper X” measuring 3.18 million SHUs, it has yet to be confirmed by Guinness World Records.)

The searing pepper didn’t sit well in the chili-eating contestant. Immediately after slaying a Reaper, the man began dry heaving and developed pain in his neck and the back of his skull. That morphed into a diffuse, painful headache. Over the next few days, he experienced thunderclap headaches at least twice—but likely more, he just couldn’t recall exactly. Thunderclap headaches are severe, sudden, with quick pains that strike like a clap of thunder rumbling through your skull. They tend to peak within 60 seconds and can be accompanied by nausea, vomiting, altered mental state, seizures, and fever. Their stormy aches can be a sign of serious problems, like bleeding in the brain, a brain infection, or a cerebrospinal fluid leak.

The pain was excruciating enough that the man went to the emergency room. But doctors didn’t find any immediate problems with him to explain the episodes. He didn’t have any slurred speech, loss of vision, neurological deficits, muscle weakness, or tingling. His blood pressure was a little high, but not extremely so, at 134/69 mmHg. Initial CT scans found no problems in his neck and head.

Hot headed

But a closer scan of blood vessels in his head found a peculiar narrowing of arteries in his brain. Based on this—and the lack of other problems—the doctors diagnosed him with reversible cerebral vasoconstriction syndrome (RCVS), a rare cerebrovascular condition caused by tightening of blood vessels in the brain and marked by a series of thunderclap headaches.

Patients with RCSV tend to recover completely over time, and it’s not always clear what causes the recovery in the first place. Certain medications and illicit drugs have been linked to it in the past, but some cases seem idiosyncratic.

The doctors noted that there are no previous reports of RCSV being caused by eating hot peppers, but there are reports of cayenne pepper causing spasms in blood vessels, as well as heart attacks. Presumably, these effects come down to capsaicin, the active ingredient in hot peppers that gives them their heat. Capsaicin is known to influence the sympathetic nervous system.

“Given the development of symptoms immediately after exposure to a known vasoactive substance, it is plausible that our patient had RCVS secondary to the ‘Carolina Reaper,’” the doctors concluded.

The only treatment for RCVS is observation and ditching whatever the suspected offending substance was—in this case the chili pepper. With supportive care, the man had no other thunderclap headaches and a scan five weeks afterward found that artery tightening had resolved itself.

BMJ Case Reports, 2018. DOI: 10.1136/bcr-2017-224085 (About DOIs).