Holm Oak Toxic?

Updated 2026-03-06| 4 min read| 1,914 found this helpful

All plant parts are toxic, with unripe fruits, leaves, bark and buds having the highest tannin concentrations

Ingestion causes kidney damage in ruminants and primary gastrointestinal distress in monogastric animals including horses

Wood dust from this species is classified as a confirmed carcinogenic substance

FAQ

Is Holm Oak toxic to Humans?

Gastrointestinal distress (abdominal pain, nausea, vomiting, bloody diarrhea); kidney damage possible with large quantity ingestion (Moderate)

Is Holm Oak toxic to Cats?

Gastrointestinal irritation (vomiting, diarrhea, abdominal pain) if ingested; no severe species-specific toxicity recorded (Moderate)

Is Holm Oak toxic to Dogs?

Gastrointestinal irritation (vomiting, diarrhea, appetite loss) if ingested; kidney damage possible with large repeated intake (Moderate)

Is Holm Oak toxic to Horses?

Symptom onset within 24 hours of ingestion: colic, gastrointestinal distress, bloody diarrhea, weakness, tachycardia, potential kidney damage in severe cases (Moderate)

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Toxicity Details

Humans

Moderate

Gastrointestinal distress (abdominal pain, nausea, vomiting, bloody diarrhea); kidney damage possible with large quantity ingestion

Cats

Moderate

Gastrointestinal irritation (vomiting, diarrhea, abdominal pain) if ingested; no severe species-specific toxicity recorded

Dogs

Moderate

Gastrointestinal irritation (vomiting, diarrhea, appetite loss) if ingested; kidney damage possible with large repeated intake

Horses

Moderate

Symptom onset within 24 hours of ingestion: colic, gastrointestinal distress, bloody diarrhea, weakness, tachycardia, potential kidney damage in severe cases

Toxicity Snapshot

Toxic PartsUnripe fruits (higher toxicity than ripe fruits), leaves, bark, buds; oak wood dust is a confirmed carcinogen

Exposure RouteIngestion of leaves, fruits, bark or buds; inhalation of wood dust during processing

Toxic CompoundsTannins; Catechins; Oligomeric tannins; Catechin gallates; Catechin glycoside; Dimeric proanthocyanidins; Ellagitannins (including vescalagin)

First Aid & Prevention

First 30 Minutes

• Remove all remaining plant material from the exposed person/animal's mouth immediately
• Induce vomiting only if explicitly directed by a medical or veterinary professional for recent ingestion
• Withhold all food and oral intake until you receive guidance from a qualified professional

Contact Vet Immediately

• If your pet or livestock has ingested any part of holm oak, even if no symptoms are present
• If symptoms like vomiting, discolored urine, lethargy, appetite loss or diarrhea appear after exposure
• If you suspect oak wood dust inhalation leading to respiratory distress in animals or humans

Prevention

• Keep holm oak plants, fallen leaves and acorns out of reach of children, pets and grazing livestock
• Wear N95+ respiratory protection when cutting or processing holm oak wood to avoid dust inhalation
• Never use holm oak branches, leaves or acorns as animal feed or bedding material

Treatment & Prognosis

• Gastrointestinal decontamination (emesis, activated charcoal) as appropriate for exposure timing
• Symptomatic supportive care including fluid therapy to protect kidney function, pain relief and anti-diarrheal medication
• Monitor kidney function for at least 72 hours post exposure in cases of significant ingestion

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Professional Toxicology

Scientific NameQuercus ilex L. (syn. Quercus sempervirens Mill.)

AliasesEvergreen Oak、Holly Oak、Stein-Eiche (German)、Chêne vert (French)、Leccio (Italian)

Toxicity Grade

HumansModerate

CatsModerate

DogsModerate

HorsesModerate

Target Organs

Gastrointestinal tractKidneysRespiratory tract (wood dust exposure)

Mechanism of Action

• Tannins and their metabolic breakdown products cause direct irritation to gastrointestinal mucosa, and damage to kidney tubule cells in susceptible species, especially ruminants

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: Most commonly affected species; symptom onset 3-5 days post ingestion, include constipation, brown discolored urine, lethargy, appetite loss, rumen stasis, increased thirst/urination, reduced milk production, bloody foul-smelling diarrhea, edema and potential kidney failure

Sheep/Goats (ruminants): Develop similar kidney damage and gastrointestinal lesions as cattle after ingestion of large quantities of plant material

Small monogastric mammals: Develop mild to moderate gastrointestinal irritation including diarrhea and appetite loss after ingestion of large amounts of plant material

Confusion Risk

The following plants look similar and may be confused:

Other oak species Quercus spp.

Visually similar to other oak species, all of which contain comparable levels of toxic tannins and pose similar ingestion risks

English holly Ilex aquifolium

Confused due to similar leaf shape and shared 'holly' common name; Ilex aquifolium is significantly more toxic than holm oak

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Related Toxic Plants

Common Oak

Quercus robur L.

Moderately toxic

Black Oak

Quercus velutina Lam.

Moderately toxic

European Beech

Fagus sylvatica L.

Low toxicity (raw nuts are toxic in large quantities)

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Data Sources

1. CliniTox (Universität Zürich)

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.