Actor Jamie Dornan was hospitalized with heart attack-like symptoms after an encounter with a toxic caterpillar, according to friend Gordon Smart.

During an appearance on BBC’s “The Good, the Bad and the Unexpected” radio show, the Scottish broadcaster explained how both men ended up with racing hearts and arm discomfort during a golf trip to Portugal last year.

After a night of drinking with the boys, Smart said he began feeling a “tingling in my left hand and tingling in my left arm,” symptoms which are “normally the sign of the start of a heart attack.”

He was taken to a local medical center, where doctors told Smart he had a heart rate of 210 BPM and sent him to the hospital. Only later, Smart learned that Dornan had also checked into the hospital after coming down with the same symptoms.

While doctors initially blamed the health scare on too much caffeine and alcohol during their getaway, a week after the incident, Smart said he got a “phone call from the doctor” who asked if the group came into contact with any caterpillars while on vacation.

It was then that they learned they likely brushed up to a processionary caterpillar on the golf course.

“It turns out that there are caterpillars on golf courses in the south of Portugal that have been killing people’s dogs and giving men in their 40s heart attacks,” Smart said.

Processionary caterpillars have tiny hairs containing a toxic protein that can trigger itching, rashes, eye irritation, sore throat, and difficulty breathing in both humans and animals, according to a page from the entomology department at the University of Florida.

“It turns out we brushed up againt processionary caterpillars and had been very lucky to come out of that one alive,” Smart added.

“So there’s my story. The good news is it wasn’t a caffeine overdose, it wasn’t a hangover. It was a poisonous, toxic caterpillar,” he concluded.