Janine Riley said her son Henry went from being an active child who was 'fit and healthy' to struggling to breathe or walk along a corridor.
One day, he was playing rugby then came home complaining of a stomach ache.
But his condition quickly worsened and in the end he was struggling to breathe and burning up.
An ambulance was called and he was rushed to hospital where Henry was diagnosed with the flu, but his condition was so bad that he was put in intensive care.
Now, Janine, 44, of Wadebridge, Cornwall, wants to warn other parents of just how bad the flu can be.
She said: "He was fine one day, playing rugby, came home with a tummy ache. We put him to bed with paracetamol and ibuprofen.
"The next day he was really poorly, very hot, struggled breathing, so we called an ambulance and within a few minutes he had been rushed to hospital.
"A few minutes more in A&E and he was taken theatre and put to sleep and he was taken to intensive care.
"It was really scary. They couldn't look after him in our hospital so they transferred him to Bristol paediatric intensive care unit, where he was on a ventilator for three days.
"But he was really lucky and did recover really well, enough to come back to our local hospital where he stayed for another two weeks.
"We had lots of physiotherapy, getting him to breathe again. He couldn't stand up, he couldn't walk.
"He'd gone in a few days from being a fit, healthy eight-year-old boy to not being able to walk down the corridor, it was really sad."
Dr Julie Yates, head of screening and immunisation at Public Health England South West, stressed the importance of flu vaccinations in children.
She said: "Flu is a really nasty bug and it is not like having a cold. It can have serious complications and can be life threatening.
"At the very least it can knock you off your feet for days.
"This means absence from school for children and time off work for parents, not to mention the possibility of spreading the bug in families especially in the older more vulnerable community."