What is Alder buckthorn?

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.

How does Alder buckthorn work?

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.

What forms does Alder buckthorn come in?

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.

Where it comes from:

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.

What does Alder buckthorn help with?

• Short-term constipation: This is the one use European regulators accept. Alder buckthorn belongs to a laxative group whose bowel effect is well established in people. It is meant for occasional use, not for daily control of the bowel. Diet, fluid and bulk fibre come first. No randomised trial of alder buckthorn bark alone was found. Regulators based their view on very long medical use and on data from close relatives such as senna.
• Hard stool where straining hurts, such as with haemorrhoids (piles) or after surgery: Tradition used the bark to make stools soft when pushing was painful. Doctors still sometimes want a soft stool after bowel or anal surgery. There is no trial evidence for alder buckthorn in this setting. Softer options, such as bulk-forming or osmotic laxatives, are usually tried first. If you have had bowel surgery, ask the surgical team before using any laxative.

What are the side effects of Alder buckthorn?

• Cramping or griping pain in the belly
• Loose or watery stools
• Nausea
• Urine turning yellow-brown or reddish (harmless)
• Low potassium with long or heavy use, causing weakness, cramps or an odd heartbeat
• Dark pigment spots in the bowel lining, seen at colonoscopy (harmless, and it fades after stopping)
• A bowel that becomes slow without the laxative, after long use

Good to know:

Cramping and loose stools are common and usually mild. They often mean the amount taken was too high.

The serious effects come from long or heavy use, not from a single dose. Potassium loss is the one that matters most, because it affects the heart.

Fresh or badly stored bark is a different matter. It can cause violent vomiting and severe cramps.

How much Alder buckthorn should you take?

• Recommended daily: This is what labels carry, not advice for you. Licensed European products usually state 10 to 30 mg per day of hydroxyanthracene derivatives (the active bark compounds), measured as glucofrangulin A. Labels tell users to take the smallest amount that gives a soft stool, once a day. Loose bark cannot be dosed this way. Its strength depends on how old the bark is, and you cannot tell that by looking. Ask a pharmacist or doctor before using it, especially if you take other medicines.
• Best time of day: Labels usually say a single dose at bedtime. The effect then lands the next morning. Taking it in the morning tends to push the effect into the evening or night.
• With or without food: Food does not matter much. Take it with a full glass of water. Drink well through the day while using it. Laxatives cause fluid loss.
• Time to effect: Usually 8 to 12 hours after a dose. Some people take longer. It may not work for you at all. If one dose does nothing, that is a reason to see a doctor, not to double up.
• How long to take it: Short. Product labels in Europe say no more than one week without medical advice. Longer use can cause potassium loss and a lazy bowel that needs the laxative to work at all. If constipation lasts beyond two weeks, that needs a doctor, not a stronger laxative.