Budding footballers could be at risk of toxic shock syndrome in rare cases, a team of doctors has warned.
Cases of toxic shock syndrome among footballers are rare
The Birmingham Children's Hospital experts cite two cases where children developed the blood infection from blisters caused by football boots.
The syndrome is rare in children - most of the 40 cases a year in the UK are linked to tampon use, the British Medical Journal reported.
But if left untreated it can cause liver and kidney failure and be fatal.
The syndrome is an infection of the blood with staphylococcus aureus - a common bacterium that normally lives harmlessly on the skin.
This bacterium produces a toxin, which in turn causes the syndrome.
It is not known what triggers the bacteria to produce the toxin. The first symptoms are described as flu-like or may involve a rash and diarrhoea.
It has become less common since the link with tampon use was recognised in the 1980s.
In the first case cited by the Birmingham doctors, a 13-year-old girl developed friction blisters over both heels after playing a competitive game of football in new boots.
She was admitted to her local hospital after developing a range of symptoms including fever, rash, abnormally low blood pressure (hypotension), vomiting and diarrhoea.
Further examination revealed a blister, 2cm in diameter, over each of her Achilles tendons containing the bacterium Staphylococcus aureus with the toxic shock syndrome gene. She was treated with antibiotics.
In the second case, a healthy 11-year-old boy played football in a new pair of boots, causing a blister on his right heel. Over the next two days he developed fever, vomiting and diarrhoea, and a rash.
Within hours of admission to hospital, his condition deteriorated and his blood pressure fell. Again, pus from the blister on his heel contained Staphylococcus aureus.
Report author Mark Taylor, a consultant at Birmingham's Children's Hospital, said cases of the syndrome in children were rare.
But he said: "These cases show that the syndrome may follow relatively trivial skin trauma.
"We suggest that doctors consider toxic shock syndrome in a child with rash, fever and hypotension.
"They need to search carefully for the primary infection, as it may not be immediately obvious, and to be aware that secondary rashes occur."
The Royal College of GPs said young footballers should not be too alarmed as cases of toxic shock syndrome from wearing football boots were likely to be extremely rare.