Katie Price's son Harvey Price will be in hospital "for at least a week" as doctors monitor his critical condition.
The 18-year-old is partially blind, autistic and has Prader-Willi syndrome.
What is the latest on Harvey Price's condition?
Harvey Price is currently in intensive care after taking ill at the Prices' Surrey home.
Katie told her fans: "I can confirm Harvey is in intensive care and in the best hands. I would like to thank the ambulance services and the hospital staff for the quick response and making him stable. X."
Harvey was taken straight to a specialist paediatric hospital after Katie noticed his rising temperature quickly.
A representative for Katie told The Sun: "His condition is very dangerous and Katie is terrified.
"He has a temperature of 42 degrees and is struggling to breathe.
"One of his conditions is adrenal failure that could cause his organs to fail and is very dangerous."
Junior, the son of Katie's ex Peter Andre, told seriously ill brother Harvey "Love you big bro" after he was rushed to hospital.
The 15-year-old sent his love to his elder sibling underneath his mum Katie Price's Instagram post confirming Harvey, 18, was in intensive care.
What is Prader-Willi syndrome?
PWS is a genetic condition that can impact muscle tone, sexual development and the function of the nervous system.
As well as this, those with Prader-Willi syndrome are more likely to have learning difficulties.
Often, it also sparks a constant desire to eat food and a permanent feeling of hunger which leads to child obesity.
However, the syndrome is very rare, with the NHS estimating that it affects "no more than one in every 15,000 children born in England".
The Prader-Will Syndrome Association UK describes the medical characteristics of the condition as:
• Hypotonia: weak muscle tone, and floppiness at birth.
• Hypogonadism: immature development of sexual organs and other sexual characteristics.
• Obesity: caused by excessive appetite and overeating (hyperphagia), and a decreased calorific requirement owing to low energy expenditure levels, although obesity is not normally a feature of those whose food intake is strictly controlled.
• Central nervous system and endocrine gland dysfunction: causing varying degrees of learning disability, short stature, hyperphagia, somnolence (excessive sleepiness), and poor emotional and social development.
Timeline of Harvey Price's battle with Prader-Willi syndrome
HARVEY A&E DASHKatie Price's son Harvey in intensive care after temperature soared to 42C
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KATIE AGONYKatie Price 'fearing the worst' as Harvey in intensive care with 42C fever
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HAVE A BUTCHERSInside EastEnders star Maisie Smith's family home with quirky loft bedroom
'there's hope'Kate Garraway fights back tears on GMB as husband Derek's battle continues