Educational information, not medical advice — ask your doctor or midwife.
Buckthorn (Rhamnus cathartica) is a thorny shrub whose bark and berries act as a harsh purgative. A purgative is something that forces the bowels to empty. This one is not gentle, and it is not safe to try at home.
Small amounts can cause violent vomiting, gripping belly pain and watery diarrhoea. Children have been poisoned by eating the black berries. Loss of fluid and salts is the main danger.
It is easy to mix up with two milder relatives. Cascara sagrada (Rhamnus purshiana) and alder buckthorn (Frangula alnus) stayed in pharmacy use for a long time. Common buckthorn was dropped, because its action was too rough to control.
The evidence verdict is short. There are no modern human trials of common buckthorn as a medicine. Long folk use tells us people used it; it does not tell us that it works or that it is safe.
The proposed action comes from a group of plant compounds called anthraquinones. Gut bacteria turn them into active forms in the large bowel. This is well described for the anthraquinone laxative family as a whole.
In people, laxatives of this type pull water into the bowel and make the bowel wall squeeze harder. That is why they empty the gut. Common buckthorn has never been tested this way in a proper human trial.
Fresh bark and fresh berries also trigger strong vomiting. In animal reports, the fresh plant is the most violent form. There is no agreed standard that makes home-prepared buckthorn safe.
In cell and animal studies, emodin and related compounds from this plant group show effects on inflammation and on tumour cells. Those are laboratory findings only. They say nothing about what the plant does in a person.
Common buckthorn is rarely sold as a modern supplement. Most people who meet it meet the living plant.
Forms it has appeared in:
- Dried bark, loose or cut, from foraging suppliers - Fresh or dried black berries, picked from hedges - Historical syrups and "purging" tinctures, no longer made - Mislabelled products that are really cascara or alder buckthorn
If a label says only "buckthorn", you cannot tell which species is inside. Sea buckthorn (Hippophae rhamnoides) is a different plant altogether and is used as a food oil. Check the Latin name before you assume anything.
Buckthorn was a standard household purge in medieval and early modern Europe. Syrup of buckthorn was made from the berries and sold through the 1600s and 1700s. Writers of the day noted that it griped badly and made people sick.
American folk and Eclectic practitioners of the 1800s carried the plant over from Europe. They listed it for stubborn constipation, for "dropsy" (old word for fluid swelling), and as a spring "cleanser".
By the late 1800s most practitioners had moved to cascara sagrada. It did the same job with less violence. Common buckthorn faded out of the materia medica and was not revived.
It was later planted widely in North America as a hedge. It escaped, and it is now treated as an invasive weed across much of the United States and Canada.
Some reactions to Buckthorn need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
If someone has eaten buckthorn berries or bark, call poison control or your emergency number now. Do not wait to see how bad it gets. This matters most for children.
Get emergency care for any of these:
- Vomiting that will not stop - Blood in the stool or in vomit - Fainting, confusion, or extreme drowsiness - Muscle weakness or cramps - A racing, slow or irregular heartbeat - No urine passed for eight hours or more - Severe belly pain
Signs of dehydration in a child need same-day care. Watch for dry mouth, no tears when crying, and fewer wet nappies.
In the United States, common buckthorn is not an approved over-the-counter laxative ingredient, and the FDA has acted against anthraquinone laxatives of this family. In Europe, herbal monographs cover alder buckthorn and cascara, not Rhamnus cathartica. Many US states and Canadian provinces also list the plant as a noxious or invasive weed, with rules about planting and sale.
If constipation is the problem, talk to a doctor or pharmacist before you try anything. They can check for a cause that needs treating, such as a thyroid problem or a medicine side effect.
Options they may raise with you:
- More fluid, more fibre in food, and more movement - A bulking fibre such as ispaghula (psyllium) - An osmotic laxative such as macrogol (polyethylene glycol) or lactulose - A short course of a tested stimulant laxative, such as senna, if they advise it - A review of any medicine that may be constipating you
Do not swap one laxative for another on your own. A pharmacist can match the option to your health and your other medicines.
Graded pages for the options named above:
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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