Smelly tongue may be caused by bacterial infection, fungal infection, tumor, etc. It is recommended to go to dentistry for timely examination and treatment. 1. Often do not brush your teeth or brush the teeth brushing is not good may lead to oral flora disorders, tongue bacterial infection, such as: anaerobic bacteria, Helicobacter pylori, etc., easy to cause oral odor, odor and bitterness. 2. If the body’s immunity is low, it is easy to be infected when contacting fungi, oral candidiasis will appear, and it will induce tongue diseases such as hairy tongue, cracked tongue, etc., and the performance of smelly tongue will appear. 3. Tongue tumors may have ulceration of the tongue, and there may be necrosis of the tissues, and the tongue coating will be smelly.