Amy Winehouse was hospitalised on Monday night for a reaction to medication but was expected to be released by morning, representatives for the Grammy-winning singer said.
An ambulance took Winehouse from her north London home to University College Hospital, spokesman Chris Goodman said.
"Doctors have advised that she will be kept under observation overnight and is likely to be released tomorrow," read a statement released by Goodman and Tracey Miller, the 24-year-old's US-based publicist.
It was the second time in as many months that Winehouse has been in the hospital. She was admitted to a London clinic in June after collapsing at home, and father Mitch Winehouse said at the time she had developed early stage emphysema from smoking cigarettes and crack cocaine.
Winehouse underwent a series of tests but was discharged in time to perform at the Glastonbury music festival and celebrations for former South African president Nelson Mandela's 90th birthday.
The troubled soul diva became an international star after she released the Grammy-winning album Back to Black in 2006, but her music has been overshadowed by reports of drug use and run-ins with the law.
This year, she was investigated by police, although not charged, after a tabloid newspaper published a video that appeared to show her smoking crack cocaine.
In April 2008 she was cautioned by police for assault after she slapped a man on a night out.
Earlier this month, her husband Blake Fielder-Civil was sentenced to 27 months in jail for assault and obstructing justice. Fielder-Civil admitted beating up pub manager James King in a barroom fight in 2006 and then offering him $400,000 to keep quiet about it.
Winehouse has repeatedly regaled concert audiences with appeals for the release of "my Blake".