In TCM the spleen (Sp) dominates or opens out into the mouth. The stomach (St) is integral to the digestive system (DS) with the spleen and the mouth is considered the opening to the DS.
Therefore imbalance in the Sp/St where there is an accumulation of dampness and heat can cause bad breath. Wherever there is heat odours will be found, and combine that with dampness which is foetid gives bad breath. Therefore herbs that clear heat and dampness are golden seal or Chinese golden thread, giant hyssop and peppermint are used.
Intestinal blockage or constipation may also be present and therefore as the Chinese proverb days "to help above, help below" it is important to restore regular bowel movements, this is particularly helped by rhubarb and mirabitilum, or glabber salts. The remaining possibility is that bad breath is caused by food stagnation so in such cases using herbs to promote digestion will solve the problem. Herbs such as radish seeds, hawthorn berry and oriental worm root are used
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