The 54-year-old "Basic Instinct" star was in the Italian city for an event organised by American Foundation for AIDS Research benefit (amFAR), reported Us magazine.
"She had fainted and was out cold. It was scary. Sharon experienced migraine related symptoms, and we all felt it best that she got checked out before the amfAR event. She was examined and given a clean bill of health. And as she said, wild horses couldn't keep her away," a representative for amFAR said.
Stone, who has three chidren, had attended the gala with boyfriend Martin Mica, 27, with whom she was photographed holding hands as they watched from the front row.
