Bitter principles—compounds found in various bitter-tasting herbs such as gentian (Gentiana lutea), wormwood (Artemisia absinthium), and others—have a long history of use in traditional medicine systems, especially in European and Asian herbal traditions. Historically, these substances were used as "bitters" to stimulate digestion, appetite, and, by extension, to relieve symptoms such as nausea and vomiting. The rationale was that the bitter taste would stimulate salivary and gastric secretions via a reflex action, thereby improving gastrointestinal function and reducing discomfort associated with indigestion, which sometimes includes nausea.

There is, however, a lack of robust scientific clinical evidence to specifically support the use of bitter principles for treating nausea and vomiting. Most studies and reviews on bitters focus on their general effects on digestive secretions and appetite stimulation rather than direct antiemetic activity. A few small studies and traditional medical texts suggest mild benefits, but systematic reviews and high-quality clinical trials are lacking or inconclusive regarding their efficacy specifically for nausea and vomiting.

In summary, the use of bitter principles for nausea and vomiting is primarily supported by traditional use. While they are still included in some herbal formulas for digestive complaints, current scientific validation for their effectiveness in this specific context is limited.