The six-year-old Sunderland fan has the rare childhood cancer neuroblastoma and his winning smile, despite his ordeal, has touched the world of football, and beyond.
A host of fundraisers have been held in Yorkshire for Bradley and he has recently been enjoying a holiday in Scarborough.An update on Facebook page Bradley Lowery's fight against Neuroblastoma said: "Bradley is deteriorating fast, his temperature is going very high his breathing very fast, his oxygen levels low.
"He is sleeping most the time apart from odd times awake. We knew this was coming but we are heart broken beyond words.
"We have been told he could be like this for days it just depends on him and his body."
It was followed by three breaking heart emojis.
The youngster's family, from Blackhall, County Durham, have used social media to regularly update his many thousands of well-wishers around the world about his condition.
But they recently had to issue a plea for people to stop asking on social media whether Bradley had died.
Bradley was a mascot for Sunderland several times last season and struck up a remarkable friendship with top scorer Jermain Defoe.
He was also a mascot for England at Wembley when his "best mate" scored in a World Cup qualifier against Lithuania in his comeback game.