Bitter herbs are thought to stimulate digestive function by increasing saliva production and promoting both stomach acid and digestive enzyme production.⁴ As a result, they are particularly used when there is low stomach acid but not in heartburn (where too much stomach acid could initially exacerbate the situation). These herbs literally taste bitter. Some examples of bitter herbs include greater celandine, wormwood, gentian,dandelion, blessed thistle, yarrow, devil’s claw, bitter orange, bitter melon, juniper, andrographis, prickly ash, and centaury.⁵. Bitters are generally taken either by mixing 1–3 ml tincture into water and sipping slowly 10–30 minutes before eating, or by making tea, which is also sipped slowly before eating.

Horehound contains a number of constituents, including alkaloids, flavonoids, diterpenes (e.g., marrubiin), and trace amounts of volatile oils.⁶ The major active constituent marrubiin and possibly its precursor, premarrubiin, are herbal bitters that increase the flow of saliva and gastric juice, thereby stimulating the appetite.⁷ Similar to horehound, elecampane has been used by herbalists to treat people with indigestion.

Carminatives (also called aromatic digestive tonics or aromatic bitters) may be used to relieve symptoms of indigestion, particularly when there is excessive gas. It is believed that carminative agents work, at least in part, by relieving spasms in the intestinal tract.⁸

The mucilage of slippery elm gives it a soothing effect for coughs. Usnea also contains mucilage, which may be helpful in easing irritating coughs. There is a long tradition of using wild cherry syrups to treat coughs. Other traditional remedies to relieve coughs include bloodroot, catnip, comfrey (the above-ground parts, not the root), horehound, elecampane, mullein, lobelia, hyssop, licorice, mallow, (Malvia sylvestris),red clover, ivy leaf, pennyroyal (Hedeoma pulegioides, Mentha pulegium),onion, (Allium cepa), and plantain (Plantago lanceolata, P. major). None of these has been investigated in human trials, so their true efficacy for relieving coughs is unknown.

Expectorant herbs help loosen bronchial secretions and make elimination of mucus easier. Numerous herbs are traditionally considered expectorants, though most of these have not been proven to have this effect in clinical trials. Horehound has expectorant properties, possibly due to the presence of a diterpene lactone in the plant, which is known as marrubiin.⁹