• Feeling very tired and exhausted all of the time and/or noticeable skin paleness
• Having lots of infections (such as ear, throat or chest) that don’t go away or keep coming back
• Having flu-like symptoms that don’t go away (such as lethargy, high temperature, being sick)
• Unexplained or excessive bleeding such as in urine, poo or when being sick
• Bruising easily or a rash of small red spots on the skin (called ‘petechiae’)
• Persistent and unexplained sweating or fever especially at night
• Aches and pains that don’t go away, especially in the bones, joints, back or legs, and may be worse at night
• Unexplained new limp or leg weakness
• Changes when going for a poo such as constipation, diarrhoea, pain or feeling of not having finished
• Feeling a lump, swelling or unusual firmness anywhere on the body, especially in the abdomen, neck, chest, pelvis or armpits
• Losing a significant and unexplained amount of weight in teenagers
• Slow growth in children
• Change in behaviour such as persistent crying and screaming in young children, sleeping a lot, being off food

It can be particularly hard to diagnose and can cause a number of different symptoms including persistent headaches, dizziness, seizures, clumsiness and being sick when waking up in the morning.

It usually affects young children under the age of six years old with symptoms such as a white glow in the eye (usually seen in photos) or other eye changes.