Winehouse has been working on her follow-up to album Back to Black
Singer Amy Winehouse is being treated at a private London clinic after a reaction to medication she was taking, her spokesman has said.
The singer was taken to the facility after she fell ill on Sunday.
"Some part of her medication is making her sick," spokesman Chris Goodman said. The medication formed "part of her ongoing treatment", he added.
Winehouse, 25, missed a court appearance by husband Blake Fielder-Civil on Monday because of her illness.
He lost an appeal against his prison sentence for assaulting a pub landlord.
Mr Fielder-Civil, 26, of Camden, north London, was sentenced to 27 months for assaulting James King at the Macbeths pub in Hoxton, east London, in 2006.
The music video assistant, who was freed on 5 November, also admitted perverting the course of justice by trying to bribe Mr King to withdraw his complaint.
In June, it emerged that Winehouse had developed the chronic lung disease emphysema after she collapsed in her north London home.
In July, she collapsed again following a reaction to medication and was taken to London's University College Hospital.
And, in August, she pulled out of a concert in Paris after she was taken ill at home, although she did not need hospital treatment.
Winehouse has been working on a new studio album, the first since 2006's Back to Black.
Earlier this month, Lucian Grange, the head of Winehouse's record label Universal, said new material he had heard for the album sounded "sensational".