Digital Spy reports that Billie Piper made her West End debut in Treats on Saturday after a 24-hour delay caused by an illness.
It says her agent told the Sunday Express: "Billie felt pretty unwell yesterday and was taken to hospital as a precautionary measure. She was not kept in and was quickly out of bed and up and around."
Responding to speculation that Piper was pregnant, she added: "I am not prepared to discuss any other rumours about her health as she is now purely concentrating on her role in the show."
The Sunday Mirror said Piper - pictured above with Treats co-stars Kris Marshall and Laurence Fox, who is also her boyfriend - was rushed to hospital on Friday night after she collapsed in agony.
Digital Spy said the first show was due to take place on Friday but had been called off amid speculation that Piper was ill or stressed out. However, according to postings on the Outpost Gallifrey Forum, the show went ahead with an understudy taking her place.
Treats, which had been in previews, is on at the Garrick Theatre until May 26.
Outpost Gallifrey reported on Friday that Piper's official debut had been delayed, although conflicting dates were circulating.