Educational information, not medical advice — ask your doctor or midwife.
Alder is the bark and leaf of the black alder tree, Alnus glutinosa. In European folk practice it was mainly a mouth and skin remedy. People made a bitter, drying wash from the dried bark for sore throats, sore gums and grazes.
The tree grows in wet ground across Europe, Ireland and western Asia. In Irish it is called fearnóg. The timber was valued for piles and clogs, but the healing use focused on bark and fresh leaves.
Here is the honest verdict on the evidence. There are no good human trials of alder for any health use. Long folk use is not proof that it works, and it is not proof that it is safe.
The short answer is that nobody has shown how alder works in people, because that has not been tested.
The bark is rich in tannins. Tannins are plant compounds that bind protein and make tissue feel tight and dry. That drying, puckering effect on the mouth is real and is why the old gargles felt soothing.
Alder bark also holds compounds called diarylheptanoids, such as oregonin. In test tube and cell studies, oregonin appears to mop up damaging molecules and damp down some markers of swelling.
In animal studies, alder bark extracts have shown mild anti-swelling effects. Lab and animal results often fail to repeat in people. Treat them as a reason to study alder, not as a reason to trust it.
Alder is a niche herb. You will not find it in most shops or pharmacies.
The forms that do exist are:
- Dried, cut bark, sold loose by specialist herb suppliers.
- Bark tincture, an alcohol extract in a dropper bottle.
- Dried leaf, sold rarely and mostly for external use.
- Home-gathered bark and leaf, in folk practice.
Fresh alder bark is not the same as dried. Fresh bark was known to cause vomiting, so old practice called for bark dried or aged for a long time before use.
There are no capsules or standardised extracts in general sale, and no official quality standard for alder in the UK, EU or US.
Alder has a long place in northern European folk life, and a modest one in folk medicine.
In Ireland and Britain, healers used boiled bark as a gargle for sore throat and as a wash for sore gums. The same wash was applied to grazes, burns and swollen skin. Fresh leaves were laid inside shoes for tired, hot feet, or bound onto a swelling.
Some older European writers listed alder bark for fevers and as a substitute for other bitter barks. It was also used for tanning hide and dyeing cloth, which tells you how much tannin the bark holds.
In Irish lore the tree carried strong meaning. Cut alder wood turns orange-red, and old stories linked that to blood. None of this was tested in the way we now test medicines.
Stop using alder and see a doctor if any of these happen.
- You vomit repeatedly, or cannot keep fluids down. - You get a rash, itching, swollen lips or tongue, or wheeze. Trouble breathing or swelling of the throat is an emergency; call emergency services. - A sore throat comes with high fever, drooling or trouble swallowing. - A skin problem spreads, turns hot and red, or leaks pus. - Your mouth or skin symptoms have not improved in about a week. - You feel unusually tired, pale or breathless, which can point to low iron.
Alder is not licensed as a medicine in the UK, the EU or the US. No health claim for it is approved.
Dried bark and tinctures are sold by specialist herb suppliers under general food supplement or botanical rules, which do not test whether it works.
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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