Why does my mouth smell bad after coffee?

Because bad breath occurs when bacteria grow in the mouth, between the teeth.

Coffee beans contain caffeine and acids, which "dry out" the oral cavity, reduce the production of saliva, respectively, creating favorable conditions for the multiplication of bacteria, which causes bad breath.

By the way, if coffee with milk, then this smell is enhanced by lactic acid.

Therefore, after a cup of coffee, it is better to chew gum or use mouthwash

Coffee causes dry mouth. This is due to the fact that it contains caffeine, approximately 200mg in 250ml of drink - being the main culprit in lowering saliva production. Dry mouth is more than just an inconvenience. The lack of saliva contributes to the creation of a favorable environment for the growth of bacteria and fungi, which in turn leads to bad breath. In addition, the lack of saliva makes it impossible to flush food debris into the stomach, which in turn leads to dental problems and the formation of caries