Yellow tongue fur

Yellow tongue fur: Yellow tongue fur usually indicates internal syndrome and heat syndrome.

During the course of a disease, the change of tongue fur from white to yellow suggests that the pathogenic factors have transformed into heat and transmitted to the interior. The yellower the tongue fur, the ~everer the pathogenic factors. Light-yellow tongue fur indicates mild heat, deep-yellow tongue fur signifies severe heat and sallow tongue fur suggests extreme heat. That is why ellow tongue fur usually appears simultaneously with red and deep-red tongue
 
Thin and yellow tongue fur indicates mild pathogenic heat, usually seen in wind-heat external syndrome, or inward invasion of heat transformed from wind-cold, or mild heat progress in internal heat syndrome. Yellow and white tongue fur suggests that the pathogenic factors are transmitted from the exterior to the interior and cold transforms into heat in exogenous disease. Yellow and greasy tongue fur is usually due to accumulation of damp-heat, or due to phlegm and fluid retention transforming into heat,or due to food retention and heat putrefaction. Yellow and  rough tongue fur is often caused by pathogenic heat consuming body fluid or by retention of heat in the intestines. But if the tongue fur is yellow, slippery and moist and the tongue is light-white and bulgy, it is due to decline of yangqi and failure of dampness and water to transform.