 [ Symptoms ] what can cause a 10 year old boy is head of hair to change from black to reddish brown in a matter of hours  my 10 year old was playing in the back yard but then started having a slight headache when he came inside i notice his hair on one side was changing in color from black to light brown i also notice he had what looked like 2 mosquito bites on his arms he had no temperature but was feeling a bit fatigued but we went on to basketball practice none the less by the end of the evening his entire head of hair was now the color reddish brown [ Disease ] i am not aware of any medical condition that would cause his hair to immediately change from black to reddish brown in this short period of time it may be wise to have him medically evaluated however