Symptoms of yin and yang deficiencies include both yin and yang deficiencies, which are characterized by thinness, lumbar and knee weakness (a feeling of weakness in the lumbar area and knees), depression, and sometimes fear of cold and sometimes fear of heat. Yin deficiency is usually characterized by dry mouth and thirst, hot flashes (bursts of heat), sweating, dry stools, a red tongue with little or no moss, and a fine pulse (a pulse that becomes narrower and thinner and quicker in rate). Yang deficiency, on the other hand, is characterized by a fear of cold and a preference for warmth, mental lethargy, lumbar and knee tenderness (a feeling of weakness and tenderness in the lumbar region and knees), and a pale tongue with a weak pulse. A combination of both deficiencies is usually characterized by a fear of cold in winter, a fear of heat in summer, fatigue (lack of energy), lack of breath, shortness of breath and laziness in speech, and a pale tongue with a thin pulse. Clinically, if Yin deficiency is predominant, Zuo Gui Wan can be used, while Yang deficiency is predominant, Right Gui Wan can be used. These two prescriptions contain both yin nourishing and yang tonifying medicines, but with different emphasis. If there is any discomfort, please consult a doctor immediately.