What is Black Alder?

Black Alder is the bark of Ilex verticillata, a holly shrub from eastern North America. American folk and Eclectic healers used it as a bitter, drying tonic. Traditional use is not proof of effect, and it is not proof of safety either: for this plant, human evidence is essentially absent.

The shrub is also called winterberry, prinos, fever bush and Virginia winterberry. It drops its leaves in autumn and keeps bright red berries through winter.

Birds eat those berries safely. People do not: they upset the human gut.

The name "black alder" causes real confusion, and that matters for safety. European black alder is a different tree, Alnus glutinosa. Alder buckthorn, Frangula alnus, is sold under similar names and acts as a strong laxative.

So check the Latin name on any label before you buy. A bag marked "black alder" may hold none of these three plants.

How does Black Alder work?

No one has shown how black alder works in people. The proposed actions come from its chemistry and from studies of related plants.

The bark is rich in tannins. In test tubes, tannins bind proteins and tighten the surface of tissue. That is the basis for the old claim that it firms up loose bowels and soothes a raw throat.

Holly plants also hold saponins, which are soap-like compounds. In lab and animal work, saponins irritate the lining of the gut.

That may explain the vomiting and loose stools the berries cause. It is not a benefit.

A bitter taste can prompt appetite and digestive juices. That has been studied for bitter plants as a group, not for this bark. Whether any of it happens in a person taking a normal amount is not established.

What forms does Black Alder come in?

Black Alder is rare in shops today. Where it is sold, you may see:

- Dried bark chips or shavings, for simmering as a decoction. - Powdered bark, sometimes in capsules. - An alcohol tincture, usually from small makers.

You may also see it outside the remedy shelf:

- Cut branches with red berries, sold as winter decoration and not as food.

Historically it was also used as a gargle and as a wash for the skin.

Two cautions about supply:

- Many products labelled "black alder" are a different plant, so look for Ilex verticillata on the label. - The berries are not sold as food anywhere, for good reason.

Where it comes from:

Black Alder had a real but modest place in 19th-century American medicine. Native peoples of eastern North America used bark teas and washes. Settlers took up the practice.

Eclectic physicians listed the plant as Prinos verticillatus in works such as King's American Dispensatory. They described it as an astringent and bitter tonic. They used it for diarrhoea, sore throats, skin sores, jaundice and dropsy (fluid swelling).

The name "fever bush" comes from its use in fevers that came and went. Some hoped it could stand in for cinchona bark and quinine in malaria. It did not, and that hope was abandoned.

Use faded in the early 20th century as effective drugs arrived. The plant survives mainly as a garden shrub. This page records that history; it is not a recommendation to use the bark yourself.

What does Black Alder help with?

• Diarrhoea (loose stools): This was the main traditional use, and it rests on the tannins in the bark. Tannins bind proteins in test tubes, which is thought to firm up the bowel lining. No human trial has tested black alder for diarrhoea. Loose stools that last more than a couple of days, or come with blood or fever, need a doctor rather than a bark tea.
• Sore throat and sore mouth, as a gargle: Eclectic writers used a bark gargle for raw throats and mouth sores. An astringent rinse can feel drying and may ease soreness briefly. That comfort effect is plausible but untested for this plant. It does nothing about strep throat or any other infection that needs treatment.
• Fevers that come and go: The old name "fever bush" records a hope, not a result. Nineteenth-century doctors wanted a local substitute for cinchona bark in malaria. It did not work and the idea was dropped. Never use black alder for a fever that keeps returning, and never in place of malaria treatment.
• Poor appetite and weak digestion: The bark is bitter, and bitter plants were given before meals as "tonics". Bitter taste may prompt digestive juices, which has been studied for bitters in general. Nothing has been shown for this bark in people. Lasting appetite loss should be checked by a doctor.
• Skin sores and ulcers, as a wash: A cooled bark wash was applied to sores, ulcers and itchy skin. Tannin-rich plant washes do dry and tighten the skin surface. Whether that helps a wound heal is not established for black alder. A sore that spreads, weeps or smells bad needs medical care.
• Jaundice and dropsy (fluid swelling): Folk use for yellow skin and swollen legs reflects old ideas about disease, not modern ones. Both signs can point to serious liver, kidney or heart problems. There is no evidence that black alder helps either one. These signs call for prompt medical assessment.

What are the side effects of Black Alder?

• Nausea
• Vomiting, especially after the berries
• Diarrhoea and stomach cramps
• Constipation with repeated tannin-rich tea
• A dry, puckering mouth
• Less iron taken in from food or tablets
• Loss of appetite
• Rash or itching, rarely and reported only anecdotally

Good to know:

Stomach and bowel upset is the common problem, and it rises with the amount taken.

The berries are the clear hazard. Eating them brings on vomiting and loose stools fairly reliably. Children are at most risk because a handful is a large dose for a small body.

Serious harm from the bark has not been reported in medical writing. That is weak reassurance, not strong: almost nobody uses it, and there is no reporting system that would catch rare problems.

How much Black Alder should you take?

• Recommended daily: No trustworthy amount can be given for black alder. There is no standard commercial product and no human study to set an amount. Old Eclectic books did list bark quantities. Those are historical records, not guidance, so this page does not repeat them. One point is firm: the red berries are not a food and should not be eaten at all.
• Best time of day: Time of day makes little difference to safety or effect. Bitter plants were traditionally taken shortly before meals. That is custom, not proven practice. One practical point: keep tannin-rich teas at least two hours away from iron tablets.
• With or without food: Taking it with or just after food is gentler on the stomach. Saponins and tannins are more likely to cause nausea on an empty stomach. The bitter-tonic tradition pointed the other way, before meals. That trade-off has never been tested. Avoid taking it with an iron supplement or a big iron-rich meal at the same time.
• Time to effect: Honestly, this is unknown. No trial has measured how fast black alder acts, or whether it acts at all. An astringent gargle feels drying within seconds. That is a taste and texture effect, not healing. It is quite possible the bark does nothing for your complaint. Treat any change you notice with caution.
• How long to take it: No safe length of use can be stated, because no one has studied it. Astringent barks were traditionally used for days, not months. Tannin-rich teas taken for weeks can irritate the gut and cut how much iron your body takes in. If a complaint has not settled within a few days, the answer is a doctor, not a longer course.