It is often said that the Spleen can suffer only from Yang deficiency: it is true that this is a very common pathology of the Spleen but not the only one. Indeed, the Spleen can suffer from Yin deficiency.
A deficiency of Spleen-Yin does not usually occur on its own but it is associated with Stomach-Yin deficiency. Therefore, the symptoms of Spleen-Yin deficiency resemble those of Stomach-Yin deficiency (a dry mouth with desire to sip liquids, slight epigastric pain, tongue without coating). In addition to these, the symptoms of Spleen-Yin deficiency are dry lips and dry stools.
There are particular cracks on the tongue that are typical of Spleen-Yin deficiency: these are small, transversal cracks on the sides (see picture). The formula to nourish Spleen-Yin is sha Shen Mai Dong Tang. If the Spleen-Yin deficiency is mild, Shen Ling Bai Zhu San may be used.