Chris Goodman says Winehouse was admitted to the London Clinic on Sunday. He declined to identify the medication that caused the reaction.
The 25-year-old Grammy winner has a history of drug problems and has been in and out of hospitals this year.
On Monday, a British court rejected an appeal by Winehouse's husband, Blake Fielder-Civil, against his sentence for assault and obstructing justice. The judges urged him to continue making progress at a drug rehabilitation center.
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