Topical preparations containing calendula, chickweed, or oak bark⁴have been used traditionally to treat people with eczema but none of these has been studied in scientific research focusing on people with eczema.

Historically, herbs known as astringents have been used to soothe the pain of canker sores. These herbs usually contain tannins that can bind up fluids and possibly relieve inflammation. They are used as a mouth rinse and then are spit out. None of these herbs has been studied in modern times. Examples of astringent herbs include agrimony, cranesbill, tormentil, oak, periwinkle, and witch hazel. Witch hazel is approved by the German Commission E for local inflammations of the mouth, presumably a condition that includes canker sores.

Cinnamon has been used historically for the treatment of various menstrual disorders, including heavy menstruation.⁵ This is also the case with shepherd’s purse (Capsella bursa-pastoris).⁶ Other herbs known as astringents (tannin-containing plants that tend to decrease discharges), such as cranesbill, periwinkle, witch hazel, and oak, were traditionally used for heavy menstruation. Human trials are lacking, so the usefulness of these herbs is unknown. Black horehound was sometimes used traditionally for heavy periods, though this approach has not been investigated by modern research.

Cinnamon has been used historically for the treatment of various menstrual disorders, including heavy menstruation.⁷ This is also the case with shepherd’s purse (Capsella bursa-pastoris).⁸ Other herbs known as astringents (tannin-containing plants that tend to decrease discharges), such as cranesbill, periwinkle, witch hazel, and oak, were traditionally used for heavy menstruation. Human trials are lacking, so the usefulness of these herbs is unknown. Black horehound was sometimes used traditionally for heavy periods, though this approach has not been investigated by modern research.

Tannin-containing herbs may be helpful to decrease diarrhea during acute flare-ups and have been used for this purpose in traditional medicine. A preliminary trial using isolated tannins in the course of usual drug therapy for Crohn’s disease found them to be more effective for reducing diarrhea than was no additional treatment.⁹ Tannin-containing herbs of potential benefit include agrimony (Agrimonia spp.), green tea, oak, witch hazel, and cranesbill. Use of such herbs should be discontinued before the diarrhea is completely resolved; otherwise the disease may be aggravated.

In laboratory experiments, a tannin in oak, known as ellagitannin, inhibited intestinal secretion,¹⁰ which may help resolve diarrhea. Oak is well regarded in Germany, where it is recommended (along with plenty of electrolyte-containing fluids) to treat mild, acute diarrhea in children.¹¹