Wendy Passmore heard 12-year-old Chloe in distress and struggling to breathe when she suffered the attack in her bedroom after taking a shower.
But despite using her inhaler, Chloe couldn't get her breath back and was rushed to hospital where doctors tried in vain to save her.
The tragedy was told at an inquest in Lancaster where the deputy coroner ruled that Chloe had died from natural causes.
The inquest heard that she had first been diagnosed with asthma in 2006. She had been hospitalised twice in 2011 after suffering asthma attacks.
The day before her death, she had been off school after feeling breathless during the night.
Dr Stefani Bitetti, consultant paediatric pathologist, said: "In my opinion, Chloe Passmore died as a result of an acute and fatal asthma attack."
Dr Graeme Meachie, a local GP , said Chloe had been to the doctors many times with asthma complaints and had been given a brown preventativeinhaler as well as her usual inhaler which gave immediate relief.
Simon Jones, deputy coroner, said there was evidence Chloe's asthma was not being 'well controlled'.
But he said: "It would appear that in the last 24 to 36 months of Chloe's life the usage of her medication was in line with what (Dr Meachie) expected."
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