Educational information, not medical advice — ask your doctor or midwife.
Alder buckthorn is the dried, aged bark of a European shrub, Frangula alnus. It is used as a stimulant laxative for short bouts of constipation. In German it is called Faulbaum.
The bark must be aged for about a year, or heat-treated, before anyone uses it. Fresh bark causes violent vomiting and gut cramps. Licensed products are made from bark that has been treated and tested.
Here is the honest verdict on the evidence. The laxative effect of this family of plant compounds is well accepted, and European regulators allow the claim. Trials of alder buckthorn itself are very thin.
Long folk use is not proof that a remedy works. It is also not proof that a remedy is safe.
Alder buckthorn works by irritating the lining of the large bowel. That speeds up the bowel and brings water into it.
The bark holds anthraquinone glycosides (plant compounds bound to a sugar). These pass through the stomach and small bowel mostly unchanged. Bacteria in the colon then cut off the sugar and free the active form.
The freed compounds act on the bowel wall. In animal and human work with this group of laxatives, they boost muscle contractions and cut how much water the bowel soaks up. The stool stays softer and moves on.
This pathway is well described for anthraquinone laxatives as a whole. Direct study of alder buckthorn on its own is limited. Most of what is said about it is borrowed from senna and cascara.
Alder buckthorn is sold in a few plain forms.
- Dried cut bark, brewed as a tea or blended with other herbs in packaged laxative teas. - Tablets or capsules of a dry extract, measured for strength. - Liquid extract or tincture.
In Europe, some of these are licensed herbal medicines. Those carry a tested, stated strength and a short use limit on the box.
Loose bark bought from a market has no such testing. The age of the bark, and so its harshness, cannot be judged by eye.
Alder buckthorn bark was a standard purgative in European folk practice for centuries. Records of its use run from the medieval period onward.
Village practice held that the bark had to be stored for a year before anyone touched it. That rule was learned the hard way, from the sickness fresh bark caused. German speakers knew the shrub as Faulbaum.
The bark entered European pharmacopoeias in the 1800s. It sat alongside cascara and senna as a common bowel remedy. The wood was also prized for charcoal used in gunpowder.
Past use tells you the plant was common and cheap. It does not tell you the plant is safe for you now.
Stop and see a doctor if any of these happen.
- Your belly pain is severe, or it keeps getting worse. - You see blood in your stool, or your stool is black and tarry. - Nothing moves after using it as directed. - Constipation lasts more than two weeks. - You feel weak, dizzy, or notice a racing or odd heartbeat. - You are vomiting and cannot keep fluids down.
Get urgent care for a hard, swollen belly with vomiting and no wind passing. That can mean a blocked bowel.
In the European Union and the UK, alder buckthorn bark is sold in licensed herbal medicines for short-term constipation. EU rules have placed its use in food supplements under review, so supplement sales are restricted.
In the United States it is not approved in the over-the-counter laxative monograph, though it appears in some supplements.
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 →
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