Ungaro's collection, created with the help of Lindsay Lohan, could make or break couture house

Many words have been used to describe the actress Lindsay Lohan: alcohol-abuser, self-destructive, bad girl. Designer, however, is not one of them.

Nevertheless, today at the Paris Fashion Show, still regarded as one of the premier showcases for the world's couture houses, that is precisely how she will be styling herself. LiLo has been twittering about her latest venture as "creative adviser" to no less a fashion giant than Emanuel Ungaro, one of France's most sophisticated clothes firms.

The fashion world was stunned when Ungaro announced last month that Lohan would be its new creative adviser, working with the little-known Spanish designer Estrella Archs.

Lohan, 23, star of Herbie Fully Loaded, Freaky Friday and Mean Girls, is better known for her revolutions through rehab clinics and a drink-driving arrest, as well as her relationship with DJ Samantha Ronson, than for any design ability.

But her collection could make or break the house, which has seen its fortunes decline since Ungaro retired in 2004. If it is ill-received it could permanently damage the house's sophisticated reputation.

Inevitably, there is scepticism about how much work Lohan has put into the creations. Archs studied at London's Central St Martin's, with a stint at Prada and Nina Ricci before starting her own small house.

Lohan has been pictured doing a lot of partying in Paris this week and inviting her celebrity friends, such as Miley Cyrus and Lily Allen, to "her" fashion show via Twitter.

The designs are described as bold and bright, with pink and orange colours, sequins and leather tailoring.

It is a high-risk strategy for the haute couture house. Whereas famous names such as Kate Moss and Kylie Minogue have "inspired" or put their names to designs in the past, it's been for high street chains such as Topshop and H&M, rather than a high-end couture house.

"This is the real me," Lohan said yesterday. "Working with Estrella and the team at Ungaro is a dream come true. Fashion is one of my favourite things in the world and this is the best week of my life. I'm just so excited; it has hardly hit me yet."

The British designer Zandra Rhodes said that using celebrity was part of the business today.

"We're in a period now where celebrities, whether they are muses or anything else, are going to sell," she said. "There was a time when it was the models on the catwalk, now its footballers' wives or actresses. It's a phenomenon that does not relate to the product.

"The test is whether people look at the clothes and say I must wear that. If they do, then it works; if they don't, then it won't sell.

"You could say that Vivienne Westwood's punk clothing was driven by the Sex Pistols, rather than the other way round."

The Dutch design duo Viktor and Rolf called on the singer Rosin Murphy to sing live yesterday during their show, continuing their penchant for live accompaniment – in the past Tori Amos and Rufus Wainwright have helped out.

Viktor and Rolf, whose last two collections received a muted response from the world's fashion press, pulled off a return to form, with elaborate frills and big-shaped dresses cut and shredded – just about getting right their tussle between the theatrical and commercial.

"There's a certain aggression to it, to the act of cutting, and we like that because that way it becomes contemporary," they said. "We didn't just want to create plain ball gowns."