Some of the substances found in cranesbill are tannins, gallic acid, starch, pectin, and resin. The root can contain between 12 to 25 percent tannin, with the highest amount just before flowering.
The American cranesbill is not the only plant of the genus Geranium that is used in herbal medicine. The European species wood cranesbill (Geranium sylvaticum) and herb Robert (Geranium robertianum) are also used.
The early Native Americans used this herb to treat many medical conditions including dysentery and diarrhea. It was used as an eyewash and the powdered root, often mixed with other herbs, was used as a compress on wounds and swollen feet.
The Ojibwe or Chippewa used the dried and powdered roots (rhizomes) to remedy mouth ulcers, inflamed gums and sore throat. The Blackfoot tribe employed it to stop hemorrhages.
The plant was later used by the European settlers in North America for diarrhea, internal bleeding, cholera and sexually transmitted diseases.
Due to the high tannin content the herb it has both astringent and antiseptic properties.
Today’s herbal medicine employs the herb for irritable bowel syndrome (IBS), diarrhea (especially in children and the elderly), dysentery, gastro-intestinal catarrh, ulcers, colitis as well as hemorrhoids.
Cranesbill possesses hemostatic properties and can work as an agent to stop internal hemorrhages.
In addition, the herb is used for hemoptysis (expelling blood or bloody mucus), hematuria (presence of blood in urine) and heavy menstrual bleeding and externally to stop bleeding and heal wounds.
As a mouthwash or gargle, the herb can be effective against thrush, inflammation of the mouth and throat, tonsillitis and toothaches.
The fresh leaves can also be rubbed on insect stings and used as a mosquito repellant.
It has been found that cranesbill is very active against the bacteria that cause tuberculosis.
Both the flowers and leaves are edible but are sour or bitter in taste. The flowers are often used as a garnish.