Red raspberry, blackberry, and blueberry leaves contain astringent tannins that are helpful for soothing sore throats.⁴Sage tea may be gargled to soothe a sore throat. All of these remedies are used traditionally, but they are currently not supported by modern research.

Blueberry contains similar constituents as cranberry, and might also prevent bacteria from attaching to the lining of the urinary bladder.⁵ However, studies have not yet been done to determine if blueberry can help prevent bladder infections.

Asparagus (Asparagus officinalis), birch (Betula spp.), couch grass (Agropyron repens), goldenrod (Solidago virgaurea),horsetail, Java tea (Orthosiphon stamineus), lovage (Levisticum officinale), parsley (Petroselinum crispum), spiny restharrow (Ononis spinosa), and nettle are approved in Germany as part of the therapy of people with UTIs. These herbs appear to work by increasing urinary volume and supposedly helping to flush bacteria out of the urinary tract.⁶Juniper is used in a similar fashion by many doctors. Generally, these plants are taken as tea.

Astringent herbs traditionally used for diarrhea include blackberry leaves, blackberry root bark, blueberry leaves, and red raspberry leaves.⁷ Raspberry leaves are high in tannins and, like blackberry, may relieve acute diarrhea. A close cousin of the blueberry, bilberry, has been used traditionally in Germany for adults and children with diarrhea.⁸ Only dried berries or juice should be used—fresh berries may worsen diarrhea.

Cranesbill has been used by several of the indigenous tribes of North America to treat diarrhea. The tannins in cranesbill likely account for the anti-diarrheal activity⁹—although there has been little scientific research to clarify cranesbill’s constituents and actions.