A bitter-tasting substance or formula used to increase a deficient appetite, improve the acidity of stomach secretions and protein digestion, and slightly speed up the orderly emptying of the stomach. A good bitter tonic should possess little, if any, drug effect, only acting on oral and stomach functions and secretions. Dry mouth, bad gums, teeth problems with bad breath in the morning, and weak digestion, often with constipation, are the main deficiency symptoms. A bitter tonic has little effect in normal digestion. Example: Gentiana