The Carolina Reaper, known as the world’s spiciest chili pepper, nearly claimed its first victim.

After downing one of the peppers during an eating competition, one unfortunate man developed a mysterious pain in his neck near the base of his skull. Over the next two days, he was stricken with intense headaches that came on lightning fast with ferocious intensity.

Doctors refer to these as “thunderclap” headaches. They’re identified by the severity of the headache and the rapidity with which they reach maximum intensity.

A thunderclap may come on and hit its painful crescendo in less than a minute. Some patients report that they come on even quicker — almost instantaneously.

“It feels like an explosion in the head or like being hit on the head,” Dr. Todd Schwedt, professor of neurology at the Mayo Clinic in Phoenix, told Healthline. “So it is the rapidity with which a thunderclap headache reaches its maximum that differentiates it from other severe headaches like migraines which come on more slowly.

Diagnosis: RCVS

Following at least two thunderclap headaches, the pepper-eating man sought medical help in an emergency room at the Bassett Medical Center in Cooperstown, New York, according to the journal BMJ Case Reports.

At first, doctors didn’t find any immediate cause for the headaches.

The man’s blood pressure was slightly elevated, but he didn’t have any telltale signs — such as slurred speech, loss of vision, or tingling — of more severe neurological problems.

Initial scans of his brain didn’t turn up anything either.

But, eventually the doctors treating the patient were able to diagnose him with reversible cerebral vasoconstriction syndrome (RCVS). RCVS is a rare condition in which blood flow in several arteries in the brain is temporarily constricted.

A variety of external factors can cause RCVS, including prescription medications, caffeine, energy drinks, and certain illicit drugs.

RCVS patients tend to recover over time, but in a minority of cases it can lead to stroke, causing lasting neurological problems.

Pepper prognosis

Thunderclap headaches as a result of RCVS are not uncommon, although prior to the incident above, there was no medical record of hot peppers causing them.

However, given what is known about how hot peppers interact with the body, it’s not entirely surprising either.

“Although this was certainly a unique case, it does make sense how eating such a hot pepper could cause a thunderclap headache due to RCVS,” said Schwedt.

“Capsaicin, which is a component of chili peppers, activates the sympathetic nervous system. Overactivity of the sympathetic nervous system is a proposed mechanism for RCVS, a syndrome which manifests with thunderclap headaches,” he explained.

Most are aware of the immediate effects of spicy peppers when they are consumed: burning mouth and tongue, sweating, and feeling hot.

The body’s reaction typically isn’t dangerous and most individuals can consume hot peppers with little fear of an adverse reaction.

But hot peppers, or more specifically capsaicin, have been linked to actual cardiovascular problems previously in medical literature — though not RCVS or thunderclap headaches.

A 2012 report in the International Journal of Emergency Medicine, details an incident of a 25-year-old man suffering a heart attack after consuming cayenne pepper pills.

Researchers concluded that the pills, which are often consumed as a weight loss drug, were the cause of a coronary vasospasm, constricting the blood flow in the heart.

“This case highlights the potential danger of capsaicin, even when used by otherwise healthy individuals,” the study authors wrote.

Serious conditions

Despite the unusual nature of RCVS resulting from a hot pepper, Schwedt warns that often thunderclap headaches can be a sign of more dangerous neurological conditions.

“A thunderclap headache needs to be considered an emergency,” he said. “Although there are many potential reasons to have a thunderclap headache, one cause is a subarachnoid hemorrhage (bleeding in the head) due to rupture of an aneurysm. This requires emergent evaluation and treatment.”

Subarachnoid hemorrhage must be the first consideration when dealing with thunderclap headaches.

Severe hypertension, leakage of spinal fluid, and other cerebral blockages are serious conditions that may also manifest through thunderclap headaches.

In defense of the ‘reaper’

As for the hothead who ended up in the emergency room, his symptoms eventually cleared up after about five weeks. A scan of his brain revealed that the blood vessels in his brain had returned to normal size.

Although he’ll probably refrain from the next opportunity to take part in a hot-pepper-eating competition.

Meanwhile, defenders of the Carolina Reaper have begun responding to the man’s story, speaking out in its defense and insisting the pepper is fine and safe to eat as long as it’s done so correctly.

“We have sold, in the past couple of years or so, over half a million Carolina Reapers and I have never had any knowledge or any complaint of anyone having to be hospitalized,” Salvatore Genovese, a pepper farmer in the United Kingdom told Sky News.

"It's not really designed to ... just plonk it in your mouth and eat it ... I would never do that and I wouldn't recommend it,” said Genovese.