Educational information, not medical advice — ask your doctor or midwife.
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Cranesbill is the dried root of a North American woodland plant, Geranium maculatum. It is used as an astringent, meaning a substance that tightens and dries surface tissue. Folk practice uses it for short bouts of diarrhoea, for mouth sores and bleeding gums, and as a gargle for a raw throat.
The evidence verdict is short and plain: no human trials of cranesbill have been published, so its reputation rests on long use rather than on proof. A long record of use tells you people kept reaching for it; it does not tell you the herb works.
You will meet it as a tea, a tincture (an alcohol extract) or a mouth rinse. It is meant as a short-term helper for a passing problem, not as a treatment for any ongoing bowel or gum disease.
Cranesbill root is very rich in tannins, the same drying compounds that make strong black tea taste puckery.
Tannins bind to proteins on the surface of a sore or weeping membrane. The idea is that this forms a thin, tight layer that slows oozing and fluid loss for a short time.
This explanation comes from plant chemistry and laboratory work, not from testing in people. Nobody has measured whether that surface effect changes how fast a real illness settles.
The most common forms are dried cut root for tea, a liquid tincture, and powdered root in capsules. A strong tea is also used cold as a mouth rinse or gargle.
The tea is usually made as a decoction, which means the root is simmered rather than steeped. Simmering pulls more tannin out of the tough root than hot water alone.
Strengths vary a lot between brands. Choose a product that names Geranium maculatum on the label, since other plants are also sold as "cranesbill" or "alum root".
Cranesbill was used by several Native American nations for diarrhoea, mouth sores and bleeding, and it was taken up by settlers from there. Nineteenth-century Eclectic and Physiomedical doctors in the United States listed it as a standard astringent.
It appeared in the United States Pharmacopoeia in the 1800s and remains a fixture in Western herbal manuals today.
See a doctor if diarrhoea lasts more than two days, if you see blood or black colour in the stool, or if you have a fever with it.
Get help the same day for signs of dehydration: very little urine, dizziness on standing, a dry mouth, or drowsiness. Dehydration comes on fast in young children and older adults.
Also see a doctor if your gums bleed regularly, if a mouth ulcer has not healed in three weeks, or if you notice yellow skin or eyes, dark urine or pain in the upper right belly. Stop taking it and seek advice if you get a rash, swelling or trouble breathing.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Cranesbill is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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