← The ApothecaryFagaceaebark of young branchesFact-checked 23 October 2026

English oak (Pedunculate oak)

Quercus robur

Also calledStieleiche (German) · Chêne pédonculé (French) · Roble (Spanish) · Drys (Greek)

In older monographsQuercus pedunculata

Oak bark, rich in tannins (8–20%), is one of Europe's classic astringents: the same chemistry that tans leather tightens inflamed skin and mucous membranes. The EU recognises traditional use for mild diarrhoea, minor mouth and skin inflammation, and itching haemorrhoids, all for short courses; there are no controlled trials.

Full natural-history sheet →

What it is used for

Diarrhoea
Traditional
EU traditional-use indication for symptomatic treatment of mild diarrhoea, for no more than 3 days; based on long use, not trials.^1,2
Mouth ulcers and gum health
Traditional
EU traditional-use indication: a decoction used as a mouth rinse for minor inflammation of the oral mucosa, for up to a week.¹
Sore throat
Traditional
Gargles of oak bark infusion for sore throat are recorded in European folk medicine; the EU monograph covers inflammation of the mouth rather than the throat.²
Eczema and dermatitis
Traditional
EU traditional-use indication for minor skin inflammation, as rinses, poultices or baths; in dermatology tannins are used to dry oozing skin. No controlled trials.^1,2
Haemorrhoids
Traditional
EU traditional-use indication for itching and burning of haemorrhoids, as a sitz bath, once a doctor has ruled out serious disease.¹

How it is prepared

decoction

Cut bark simmered in water and drunk.

EU herbal monograph (2010): 3 g cut bark in 250 ml water, 3 times daily, for no more than 3 days (adults).

Diarrhoea

gargle / mouthwash

A strong decoction used as a mouth rinse.

EU herbal monograph (2010): decoction of 20 g per litre, used several times daily for up to a week.

Mouth ulcers and gum health

bath

A decoction added to a full or partial (sitz) bath of about 20 minutes.

EU herbal monograph (2010): 5 g bark per litre of bath water, one bath daily, for up to a week.

Eczema and dermatitis · Haemorrhoids

dry extract / capsule

Powdered bark or dry extract in capsules or tablets.

EU herbal monograph (2010): 1 g powdered bark 3 times daily, or 140 mg dry extract 4 times daily, for no more than 3 days.

Diarrhoea

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy: Insufficient data
Breastfeeding: Insufficient data
Children: EU monograph: not recommended under 18 years for lack of adequate data.

Interactions with medicines

any oral medicineMinorTannins may delay absorption of medicines taken at the same time; the EU monograph advises separating doses by at least one hour.

Interaction checker →

Do not use if

As a bath: open wounds, large areas of damaged skin or mucosa, or skin infections (EU monograph)
Hot baths: fever, infectious illness, heart failure or high blood pressure

Side effects

Allergic reactions (frequency not known)

Toxicity

Fresh oak leaves and acorns poison grazing animals, especially cattle, through hydrolysable tannins; outbreaks in Europe involved Q. robur. The EMA notes no overdose cases in people. Recurrent diarrhoea, bloody stools or rectal bleeding need a doctor, not oak bark.

In the healing traditions

Ancient Roman medicine
Robur / quercus
The bark and the membrane beneath it said to be more powerful than the acorns; a decoction given for coeliac affections and dysentery, and the bark boiled in cows' milk applied to snake bites.
Pliny the Elder, Natural History XXIV.3
European folk medicine
Eichenrinde / oak bark
Infusions for diarrhoea, gargles for sore throat, and hot foot baths for sweaty feet and sprained ankles; also for ulcers, toothache and rheumatism.
Western herbalism
Oak bark
Topical astringent for burns and wounds and internal astringent for gastritis and diarrhoea, recorded from Dioscorides through Bock (1565) and Matthiolus (1626).

Active compounds

ellagitannins and gallotannins: hydrolysable tannins; bind and precipitate surface proteins, forming a protective layer
condensed tannins (proanthocyanidins): oligomeric catechins; astringent
gallic acid and ellagic acid: phenolic acids released when the tannins break down

History

The oak was sacred to the Greeks, Romans and Celts. Pliny thought its bark more powerful than its acorns and gave it for dysentery. Oak bark was the chief tanning agent for European leather from medieval times, and powdered Q. robur bark is still used to prevent diarrhoea in farm animals.

Sources

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.