Astringents tighten tissue through the action of tannins, which precipitate proteins to create a protective layer. They reduce surface irritation and inflammation, create a barrier against infection, and are vital for wound healing and digestive conditions. When applied externally to stop bleeding, they are called styptics.

Bitter herbs are of major importance to the digestive system and overall health. When tasted, they trigger the release of the digestive hormone gastrin, which stimulates appetite, digestive juices, liver detoxification, bile flow, blood sugar regulation, and gut wall repair. They must be tasted to work — capsules bypass their mechanism.

Cardiac remedies have actions on the heart, ranging from powerful cardioactive agents like Digitalis (foxglove) to gentler cardiotonics like Crataegus (hawthorn) and Tilia (linden). Cardiotonics benefit the heart through flavones without cardiac glycosides; cardioactive herbs contain glycosides that can accumulate dangerously.

Carminatives ease flatulence discomfort through their volatile oil content, which has local anti-inflammatory and antispasmodic effects on the gut lining and muscle coats. Key constituents include terpene oils like farnesene, thymol, and carvacrol.

Cholagogues stimulate the flow of bile from the liver. Bile aids fat digestion and acts as a natural laxative. Most bitters and hepatics are also cholagogues. They support liver health and systemic detoxification, but are contraindicated in painful gallstones, acute bilious colic, obstructive jaundice, and acute viral hepatitis.

Demulcent herbs soothe and protect inflamed or irritated tissue through their mucilage content — large, complex sugar molecules that form a gel-like coating. They are especially valuable for the digestive and respiratory systems, creating a protective barrier that reduces irritation and inflammation.