Prolonged low fever and yellowish tongue coating are mainly due to the presence of dampness and heat in the body, and should be treated with drugs that clear away heat and eliminate dampness, such as Artemisia capillaris soup.
In Chinese medicine, yellow and greasy tongue coating is one of the typical manifestations of dampness-heat syndrome, while low-grade fever is a manifestation of heat syndrome, so the above symptoms are mostly considered to be the presence of dampness-heat evil in the body. In addition to the above symptoms, this syndrome may also present with drowsiness in the head and body, low food intake, abdominal distension, nausea, bitter taste in the mouth, irregular bowel movements, yellow-brown odor, burning in the anus, dampness and itching in the pubic area, eczema, jaundice, and so on.
Clinically, the main drugs used for this syndrome are those that clear heat and relieve dampness, such as Yin Chen Artemisia Tang and Long Guo Diarrhea Liver Tang. Consult your doctor for specific medications.