Lily Allen is battling blood poisoning just days after suffering her second miscarriage, doctors have said.

The 25-year-old pop star was said to be responding well to treatment for septicaemia after being taken to hospital by ambulance on Friday night.

Allen had been recovering at her home in Gloucestershire with her boyfriend Sam Cooper after losing her baby son last weekend, six months into her pregnancy.

Septicaemia is a life-threatening condition caused by bacteria invading the bloodstream from an infection. Sources include bladder infections and tooth abscesses. The condition can also occur after a miscarriage.

A message from Allen's publicist said the singer was responding well in hospital and her condition was improving.

Allen started dating 32-year-old Cooper, a builder, last year. She had begun to wind up her music career to prepare for motherhood although she performed at the Wireless festival in London in the summer. Allen had also set up a vintage clothing business, Lucy In Disguise, with her elder sister Sarah Owen.

Allen has released two best-selling albums – Alright, Still and It's Not Me, It's You – and has had hit singles including The Fear and Smile.

The singer-songwriter had a miscarriage in 2008 that she described as "the worst time of her life". This summer she announced she was pregnant again after being given the all-clear at her three-month scan. In an interview shortly afterwards, Allen, the daughter of the actor Keith Allen and the screenwriter Alison Owen, admitted that she was "living in fear" of losing the baby and that she had already suffered complications.

After her miscarriage last week Allen indicated she was unwell to fans via Twitter: "I'm still very sick but the messages are helping me to be stronger. Thank you xx."