An ambulance was called to the 24-year-old singer’s house in Camden, north London and she was taken to the accident and emergency unit at University College Hospital at around 8.40pm.
Police were stationed outside her house as Winehouse was brought out in a wheelchair while wrapped in a blanket and given oxygen. Her father Mitch Winehouse was with her.
Her spokesman Chris Goodman said: “Amy Winehouse suffered a reaction to medication at home this evening and was taken to hospital.
“Doctors have advised that she will be kept under observation overnight and is likely to be released tomorrow.”
A spokeswoman for London Ambulance Service said: “We were called at approximately 8.40pm to an address in NW1 to reports of an adult female taken unwell.
“We sent an ambulance and a fast response car and the patient has been taken to hospital.”
A hospital spokesman said Ms Winehouse was in a stable condition and medics would make a decision whether to discharge her this morning.
The spokesman added they expected her to go home tomorrow if she has a comfortable night.
Mr Winehouse entered the hospital at around 11.50pm and asked reporters and photographers to leave the family alone.
When asked how serious his daughter’s condition was, he held up a bag of KFC and replied: “This is how serious it is.”
Winehouse, who is being treated for an addiction to crack cocaine, is also suffering from emphysema and was admitted to hospital after collapsing at her home last month.
Mr Winehouse said in June: “It’s in its early stages, but had it gone on for another month they painted a very vivid picture of her sitting there with a mask on her face struggling to breathe.
The doctors have told her if she goes back to smoking drugs it won’t just ruin her voice, it will kill her.”
