Ed Helms thought he was dying while filming The Hangover

The Hangover movies look like they would have been incredible fun to shoot - if a little (okay, a lot) chaotic.

A group of pals hanging out in amazing cities and getting up to all sorts of weird sh*t - what's not to love? I'm sure all the stars would have had a blast... that is, if Ed Helms didn't literally think he was dying at the time.

After the huge success of the original Hangover movie in 2009, the gang got back together to travel to Thailand for Stu's wedding in the 2011 sequel.

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During an appearance on The Graham Norton Show to promote the movie, Bradley Cooper explained the cast and crew spent one month filming in Los Angeles before relocating to Thailand to get the shots they needed abroad.

On screen, we see Stu, Phil and Alan attempt to retrace their steps and find out what series of events led them to waking up with face tattoos, shaved heads and a new pet monkey.

Behind the scenes, there was a whole other type of disaster going on.

Helms told Graham he went through a 'rough patch' while filming, explaining he got very, very ill after eating a noodle dish at a, let's say 'questionable', restaurant.

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He admitted to trying to be 'confident' about what he was eating in the hope that he wouldn't get sick, but that didn't exactly work out for him.

Plus, it doesn't sound like we're talking about your average, 24-hour stomach bug here, either.

I'll let Helms explain.

He said: "I ate something that made my body so angry that I exploded. A bomb went off in my stomach and it had two outlets."

How's that for painting a picture?

While the rest of the guests on Norton's show laughed at Helms' misfortune, the actor admitted he was seriously concerned about his health while on the show.

Warner Bros.

"I thought I was dying," he continued. "I thought I had some crazy tropical disease that no one could diagnose and I would be dead in two days.

"No family was around and I went to some really dark places," Helms said.

The actor admitted he ate barely 'anything' for six weeks out of fear of getting sick, relying instead solely on peanut butter and jelly (aka: jam) sandwiches

Though Helms obviously wasn't having a good time, he was at least able to channel his state of mind into his performance as he said he used it to 'inform Stu's character for the rest of the movie'. Impressive work.