Paramedics were called after Lindsay Lohan was found unconscious in a hotel near Los Angeles on Friday, local media reported, but emergency services said she was not taken to hospital.
The Los Angeles County Fire Department said paramedics were called to the Ritz-Carlton hotel in Marina del Rey mid-morning after a 911 call about an unconscious person, but could not confirm it was Lohan.
ABC television local affiliate KABC reported that Lohan, who is currently filming a television movie about Hollywood icon Elizabeth Taylor's stormy romance with Richard Burton, was found in the penthouse of the hotel.
It said she was taken to the hospital, but the Fire Department could not confirm the report.
Celebrity news website TMZ meanwhile reported that Lohan had been working for two days almost non-stop, including shooting parts of the movie near the hotel.
She was found "non-responsive." Paramedics responded, and determined nothing was wrong with Lindsay, TMZ reported.
The 25-year-old last week spent two hours undergoing tests in hospital after an accident that saw the car she was reportedly driving smash into an 18-wheel big rig on the Pacific Coast Highway, west of Los Angeles.
The TV movie "Liz and Dick" role is a break for Lohan, who after a promising early start has become known chiefly as a hell-raising celebrity with substance abuse problems and frequent brushes with the law.
In March, an LA judge formally ended Lohan's probation after a long string of court appearances, but told the "The Parent Trap" and "Freaky Friday" star to "stop the nightclubbing" and behave more maturely.