After months of hype, Fifty Shades of Grey mania hit fever pitch at the film’s world premiere in Berlin.

Screaming fans scrambled to get a selfie on the red carpet with stars Jamie Dornan and Dakota Johnson, who play Christian Grey and his lover Anastasia Steele.

The hotly-anticipated big screen adaptation of the X-rated book has failed to get critics hot under the collar but is expected to be a hit at the box office.

Speaking on the red carpet at the Berlin film festival, Dornan said he would be friends with his co-star Johnson and director Sam Taylor-Johnson for life.

And despite all the craziness surrounding the project, he claimed the “main core” of his life would remain the same.

The 32-year-old Northern Irish actor said: “I always say this, at the core, nothing’s going to change in my life. I’m married, I have a baby.”

Johnson, 25, said: “My expectations? I don’t have any, I just hope that people like the movie.”

Asked why there were so many women at the premiere, the American replied: “Have you seen Jamie?”

She also blasted claims that her character is subjected to abuse in the movie, calling it a “close-minded outlook”.

“No person is abused in the movie,” she added.

Taylor-Johnson, who was on the red carpet with her actor husband Aaron Taylor-Johnson, said that although there are three books in the Fifty Shades series, a sequel for the film is yet to get the green light from movie bosses.

“It’s not official. I can imagine they are waiting to see how this one does,” the 47-year-old director said.

Author E.L. James, who has found fame with the Fifty Shades book trilogy, was also in attendance.

Such is the expectation surrounding the film that firefighters in London have said they fear a rise in call-outs over people getting trapped in compromising situations as a result of the Fifty Shades effect.

A leaked memo from UK DIY store B&Q said staff have been asked to prepare for an increase in demand for rope, cable ties and tape.

The first reviews which hit the internet gave a mixed response to the film adaptation of the book, which has sold more than 100 million copies worldwide.

Justin Chang, chief film critic at Variety magazine, said it begins well and describes it as “glossy, well cast, and a consistent hoot”.

Firefighters in London have said they fear a rise in call-outs over people getting trapped in compromising situations as a result of the Fifty Shades effect

He wrote: “In telling the story of a shy young virgin and the broodingly handsome billionaire who invites her into his wonderful world of hanky-spanky, director Sam Taylor-Johnson and screenwriter Kelly Marcel have brought out a welcome element of cheeky, knowing humour that gradually recedes as the action plunges into darker, kinkier territory.”

But he warned that, far from delivering an enjoyable climax, the film gets worse towards the end. And he branded the last half-hour “punishing in more than just a literal sense”.

The Hollywood Reporter also gave the hotly-anticipated film a mixed review. It said Johnson is “captivating” as the English literature graduate who falls under Grey’s spell.

And it praises the film’s “artful restraint” explaining that “the sex scenes suggest more than those of the standard Hollywood drama without quite going there”.

But it warns fans that “it’s a slow build to the smutty bits, and one that’s disappointingly devoid of tension”.

Most scathing was Peter Bradshaw in The Guardian, who gave it one star, describing the film as “the most tasteful and soft-core depiction of sadomasochism in cinema history” and branding the performances of stars Dornan and Johnson as “strictly daytime soap”.

Tim Robey, in the Telegraph, was more positive, awarding it four stars.

“So how has it all worked out? Almost shockingly well, considering. It proves that age-old saw that great books rarely make great films, whereas barely literate junk can turn into something ripe and even electric on-screen,” he said. “The lead performances and sleek style choices sell it irresistibly to the target audience, but the film has the confidence to end bruisingly unresolved, with the structural equivalent of a slap in the face.”

The Daily Star’s Nadine Linge also gave it four stars but warned that with only three sex scenes “viewers might feel short-changed”.

“Definitely a film for women. It might be released in time for Valentine’s Day but leave the men at home. Go see it for a giggle and a swoon with the girls,” she wrote.

Cinemas are bracing themselves for massive sales as fans of the erotic book are expected to flock to the aisles to see it on the big screen.

Earlier this month, it was announced that the film had been passed by censors without any cuts.

The British Board of Film Classification (BBFC) made director Taylor-Johnson’s take on the so-called ‘mummy porn’ story an 18 certificate, but said the work “passed uncut”.

Children as young as 12 can see the film at the cinema in France after the country’s film board decided against giving it an adult certificate.

France’s classification president, Jean-François Mary, deemed that the movie “isn’t a film that ... can shock a lot of people”.

He considers the film “a romance, you could even say schmaltzy”.

The three books written by James have reportedly been translated into more than 50 languages

Taylor-Johnson admitted she had creative differences with the bestselling author, whose books have won legions of fans around the world.

She told Porter magazine: “It was difficult, I’m not going to lie. We definitely fought − but they were creative fights and we would resolve them.”

The film premieres in cinemas worldwide today.