Alder buckthorn (aged bark)

What is Alder buckthorn (aged bark)?

Alder buckthorn is the dried bark of a small shrubby tree, Frangula alnus. In the Nordic countries it is known as brakved, trollhegg or korpipaatsama. The bark is used as a short-term laxative for constipation.

Only aged bark is used. Fresh bark, or bark stored for less than a year, can cause violent vomiting and painful cramps. Drying and storing it for a year, or heating it under controlled conditions, makes it much milder.

The laxative effect in people is accepted by European drug regulators. That acceptance rests mostly on long medical use and on known pharmacology, not on modern trials. Long folk use in Scandinavia is not proof that it works, and it is not proof that it is safe.

How does Alder buckthorn (aged bark) work?

Alder buckthorn acts as a stimulant laxative. It makes the colon move stool along faster and hold more water.

Its anthraquinone glycosides pass through the small bowel mostly unchanged. Bacteria in the colon then convert them into active forms.

In laboratory and animal work, these active forms appear to do two things. They draw water and salts into the bowel. They also irritate the bowel wall so the muscle contracts more.

The end result is well documented in people. A bowel movement usually follows within about 6 to 12 hours.

Ageing matters here as well. In fresh bark the compounds sit in a harsh, reduced form. Storage or heating turns them into gentler ones.

There is no good human evidence that the bark acts on the liver, the gallbladder or worms, as folk use once held.

What forms does Alder buckthorn (aged bark) come in?

Alder buckthorn is sold in several forms. Some are loose bark, and some are made-up medicines.

Bark on its own comes as:

- Cut dried bark, brewed as a tea or decoction. - Powdered bark in capsules or tablets. - Part of mixed laxative or "digestive" tea blends, often with senna or fennel.

Made-up medicines come as:

- Standardised dry extracts in licensed herbal laxative tablets. - Syrups and liquid extracts.

In the UK and much of the EU, licensed products carry a registration number and a leaflet. These state the strength in milligrams of hydroxyanthracene derivatives.

Loose bark bought from a herb supplier carries no such guarantee. Its strength and its age can both vary.

Where it comes from:

Alder buckthorn bark was a standard purgative across Scandinavia and northern Europe. Nordic names include brakved, trollhegg and korpipaatsama.

Folk users boiled the aged bark and drank the liquid to force a bowel movement. It was also taken as a "spring cleanse" after winter. Some traditions linked the tree to trolls and used it protectively.

The plant had non-medical uses too. Its wood made fine charcoal for gunpowder, and the bark gave yellow and brown dyes.

Herbalists and apothecaries knew that the bark had to sit for a year. Fresh bark was treated as a poison that caused vomiting and griping.

The bark entered European pharmacopoeias in the 19th century and stayed there. It is still listed today as a medicinal herb for short-term use.

What does Alder buckthorn (aged bark) help with?

• Short-term relief of occasional constipation: This is the one use with real support. Anthranoid barks like this one reliably produce a bowel movement in most adults. European regulators accept the use for short-term constipation. They based that on long medical use and known pharmacology, not on new trials. Modern trials of alder buckthorn on its own are scarce. Most trial data come from senna and bisacodyl, which work the same way.
• Softer stool when passing stool hurts, such as with haemorrhoids (piles) or after anal surgery: Doctors sometimes want stool kept soft after anal surgery or during a painful fissure. Stimulant laxatives have been used that way. For this situation most guidelines prefer bulk or osmotic laxatives first. Alder buckthorn has not been tested head to head for it. This is a decision to make with your surgeon or doctor, not alone.
• Traditional use as a spring purge or cleanse: Nordic households used the bark to "clear out" the body after winter. The idea of a seasonal cleanse has no scientific basis. Emptying the bowel does not remove toxins from the body. Repeated purging can cost you fluid and potassium instead. There is no human evidence of any health benefit from this practice.
• Traditional use for liver and gallbladder complaints: Older herbals grouped bitter barks together as remedies for a "sluggish liver". Alder buckthorn was used this way. No human study supports a liver or gallbladder effect. The bark is a bowel stimulant, not a liver treatment. Yellow skin, dark urine or pain under the right ribs need a doctor, not a herb.
• Traditional use for worms and parasites: Strong purges were once used to flush out intestinal worms. The bark was one of several plants used for that. There is no human evidence that it clears any parasite. Effective and tested drugs exist for worms. If you suspect worms, ask a pharmacist or doctor for a proper test and treatment.

What are the side effects of Alder buckthorn (aged bark)?

• Cramping and griping belly pain
• Watery or urgent diarrhoea
• Nausea
• Reddish-brown or yellow urine, which is harmless
• Loss of fluid and dehydration
• Low potassium (hypokalaemia) with repeated or long use
• A bowel that works poorly without a laxative, after long use
• Dark pigment spots in the bowel lining (melanosis coli), harmless and reversible
• Severe vomiting and bloody diarrhoea if fresh or under-aged bark is used

Good to know:

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

Coloured urine looks alarming but is harmless. It fades when you stop.

The serious problems come from long or repeated use. Low potassium matters most, because it can disturb the heartbeat.

The worst reactions come from bark that was not aged properly. Those can be severe enough to need hospital care.

How much Alder buckthorn (aged bark) should you take?

• Recommended daily: Licensed European labels state the strength in milligrams of hydroxyanthracene derivatives, counted as glucofrangulin A. A common label figure for adults and children over 12 is 10 to 30 mg per day, as a single evening dose. That is what the packaging carries. It is not an instruction for you. Labels also say to use the smallest amount that gives a soft stool. Loose bark from a herb supplier has no measured strength, so the figure above cannot be applied to it.
• Best time of day: It is normally taken in the evening. The effect comes 6 to 12 hours later, so the bowel movement falls in the morning. Taking it in the morning can leave you looking for a toilet during the day.
• With or without food: Food makes little difference. It is usually taken at night with a full glass of water. Drink enough fluid through the day while using it. Laxatives make you lose water. Taking it with other medicines is not a good idea, as the faster gut transit may reduce how much of them you absorb.
• Time to effect: Usually 6 to 12 hours after a dose. Sometimes a little longer. It may do nothing at all. That can happen with weak or badly stored bark, or with constipation that has another cause. If nothing happens after one dose, do not keep increasing it. Speak to a pharmacist or doctor.
• How long to take it: Short. Labels usually say no more than about one week without medical advice. Longer use can lead to a bowel that responds poorly without a laxative. It can also drain potassium, a mineral your heart and muscles need. Constipation that lasts more than two weeks needs a doctor, not a longer course.