Moviegoers suffered seizures and vomiting after watching a shocking new horror film at the Sundance Film Festival last week.

Paramedics were rushed to a Utah cinema after one man stumbled from an advanced screening of horror film V/H/S and collapsed in the foyer convulsing.

His girlfriend was also treated by medics after she ran from the cinema and vomited, while a third woman reportedly fled the theatre in tears after the tension became too much.

The film's producer Roxanne Benjamin insisted the incidents were not marketing ploy.

Posting on Twitter, she wrote: ''It was scary and not fun, and everyone is grateful the guy and his girlfriend are OK.

One of the managers for the theater was sitting near the guy, and said he just got real, real pale and stood up and bobbed and weaved his way out the door.

Once he was in the lobby, he kind of turned around and collapsed. He seemed to go into a seizure and so we called 911.

Amazingly, she later tweeted that the couple opted to go back in and finish the film.

Segments of V/H/S, which is shot on a hand-held camera and reminiscent of 1999's infamous Blair Witch Project, follows a group of criminals as they raid an abandoned house looking for a VHS tape.

While searching the building, the group uncover a number of other VHS tapes showing sickening scenes and paranormal activity.

According to the film's co-writer Simon Barrett, paramedics were called to treat the man after he collapsed early in the screening.

Speaking to MSNBC, Barrett said V/H/S featured graphic scenes, including one where a man is chased and falls down a flight of concrete stairs, breaking his wrist.

The man apparently reacted after seeing the fracture in all its gory detail, with parts of the wrist bone sticking out of the flesh.

The man's girlfriend then ran out into the foyer and started vomiting.

Paramedics treated the couple for half an hour, before being offered tickets for another screening of V/H/S.

Barrett said the film: While very funny in parts, is also quite intense and gory, adding that elements of V/H/S were, probably be a bit difficult to take.

According to Barrett, another woman also fled the cinema in tears during the same scene the night before.

Filmakers spoke to the woman, who said she had 'just got scared'.

After spending the rest of the film in the lobby she did not return, Barrett added.