© Franz Eugen Köhler, Köhler's Medizinal-Pflanzen · Public domain · Commons
Prunus laurocerasus
Toxic🐾Lorbeerkirsche · (Prunus laurocerasus)
Rose family (Rosaceae)
Description
One of the most common hedge plants in Central Europe, cherry laurel (Rosaceae) is easy to recognise by its glossy dark-green leaves and black drupes — and is also a leading cause of plant poisoning in children and pets. Leaves, seeds, flowers and bark all contain cyanogenic glycosides (prunasin in the leaves, amygdalin in the kernels) that release hydrogen cyanide when tissue is damaged, blocking cellular respiration; just a few chewed kernels can cause severe poisoning. In the 18th and 19th centuries, distilled cherry laurel water was used as a cough remedy, but fell out of use due to unpredictable cyanide concentrations and numerous fatalities; only homeopathic preparations from dilution D6 upward are considered safe. Shredding the hedge releases cyanide vapours, so this should only be done outdoors. If poisoning is suspected, emergency services should be contacted immediately.
External use only!
This plant must NOT be taken internally. Use only as compress, salve, or bath.
CONTRAINDICATED during pregnancy
Cyanide crosses the placental barrier; even small HCN amounts can cause fetal hypoxia. Any use of cherry laurel preparations below homeopathic D6 potency is absolutely contraindicated in pregnancy.
CONTRAINDICATED during breastfeeding
Cyanide and its metabolites (thiocyanate) pass into breast milk and can cause thyroid dysfunction and respiratory depression in the infant. Breastfeeding: contraindicated.
CONTRAINDICATED for children
Children are extremely sensitive to HCN due to lower body mass. The attractive black berries of this widely used garden hedge are a leading cause of plant poisoning in paediatrics. Education on plant identity and prohibition of consumption mandatory. In case of suspected ingestion of kernels or leaves, immediate medical consultation.
Critical drug interactions with:
Atemdepressiva (Opioide wie Morphin, Codein, Fentanyl) · Benzodiazepine und Z-Substanzen (Diazepam, Lorazepam, Zolpidem)
Folk-medicinal use of cool poultices of crushed fresh leaves for skin rashes, insect bites and minor inflammations. The antiseptic effect was attributed to released HCN — obsolete today due to percutaneous absorption risk and unpredictable dose. Pure ethnographic documentation, no application recommendation.
Sporadically documented use in the 19th century of weak cherry laurel leaf infusions as an eye bath for conjunctival irritation. The application was already classified as risky in Victorian England and is strictly contraindicated today — eye contact with HCN-containing solutions causes corneal damage and systemic absorption via mucous membranes. Pure historical documentation.
Sources: [3]
Historical use of dried leaves for insect killing in collection containers (butterfly boxes, beetle collections) — released cyanide kills insects within minutes ('killing jar' of entomological practice). This use is not medicinal but documents HCN release in a practical application. Pure documentation, hazardous practice.
Historical documentation only — do NOT use
These internal applications are historically documented. This plant is highly toxic — self-treatment can cause severe poisoning or death. For documentation only, explicitly NOT a recommendation.
Historical pharmaceutical use of Aqua Laurocerasi (cherry laurel water) as sedative and antispasmodic remedy for dry irritating cough, whooping cough, asthma and stomach cramps. Distillation of fresh leaves releases hydrocyanic acid (HCN) via β-glucosidase, with concentrations of approximately 0.1 % in the distillate. Listed in the British and French Pharmacopoeias in the 19th century, became obsolete in the first half of the 20th century due to unpredictable HCN concentrations and numerous fatalities.
Preparation & dosage
Use of Tinctura Laurocerasi (cherry laurel tincture) in the 18th and 19th centuries as antitussive and mild sedative — usually in doses of 5–10 drops, never higher. The effect rests on HCN-induced inhibition of respiratory centres. Strictly obsolete today: no therapeutic window since HCN content of fresh leaves varies strongly (season, light exposure, plant age) and can differ between batches by a factor of 10.
Preparation & dosage
Food-historical use of a few drops of cherry laurel water as bitter almond flavour substitute in liqueurs, puddings and preserves (especially in Southern and Eastern Europe, 19th/early 20th century). Due to poisoning cases, use as a food flavouring is now strictly limited in the EU by Flavouring Regulation (EC) No 1334/2008 (max. 1 mg HCN/kg in foods). Domestic culinary use absolutely not recommended.
Homeopathic use of Laurocerasus (mother tincture from fresh leaves, from D3) for shortness of breath, spasmodic cough, palpitations with cyanosis and nocturnal anxiety. Usually in potencies from D6 — these no longer contain pharmacologically active HCN amounts. Homeopathic finished products are licensed in Germany, France and Switzerland under medicinal-products law.
Preparation & dosage
⚠ External use only
TOXIC — LEAVES, SEEDS, FLOWERS AND BARK. Prunus laurocerasus (cherry laurel, common laurel) is one of the most common hedge plants in Central Europe and a frequent source of poisoning in children and pets. All plant parts except ripe fruit pulp contain cyanogenic glycosides (prunasin in leaves, amygdalin in kernels) which, upon tissue damage, are converted by the plant's own enzyme β-glucosidase to hydrocyanic acid (HCN). The kernels (stones) of the black drupes contain particularly high glycoside concentrations; as few as 5–10 chewed kernels can cause severe poisoning symptoms. HCN inhibits cytochrome-c oxidase of the respiratory chain and blocks cellular oxygen utilisation. Symptoms appear within minutes to hours: bitter almond/marzipan breath odour, nausea, vomiting, headache, tachypnoea, seizures, unconsciousness, respiratory arrest. Shredding the hedge releases HCN vapours — shred only outdoors, NOT in enclosed spaces, and do not compost shredded material. In case of suspected poisoning: IMMEDIATELY call emergency services and poison control. Antidotes: hydroxocobalamin (Cyanokit®) and/or 4-dimethylaminophenol as first-line therapy. ASPCA classification (accessed 2026-08-10): toxic to dogs and cats. The ASPCA classifies the whole genus this way.
Cyanide crosses the placental barrier; even small HCN amounts can cause fetal hypoxia. Any use of cherry laurel preparations below homeopathic D6 potency is absolutely contraindicated in pregnancy.
Cyanide and its metabolites (thiocyanate) pass into breast milk and can cause thyroid dysfunction and respiratory depression in the infant. Breastfeeding: contraindicated.
Children are extremely sensitive to HCN due to lower body mass. The attractive black berries of this widely used garden hedge are a leading cause of plant poisoning in paediatrics. Education on plant identity and prohibition of consumption mandatory. In case of suspected ingestion of kernels or leaves, immediate medical consultation.
Drug interactions
Atemdepressiva (Opioide wie Morphin, Codein, Fentanyl)
Cyanide from Prunus laurocerasus preparations inhibits cytochrome-c oxidase and blocks cellular respiration; opioids additionally depress central respiratory regulation. Combination leads to rapidly progressive hypoxia with unconsciousness and respiratory arrest.
Benzodiazepine und Z-Substanzen (Diazepam, Lorazepam, Zolpidem)
Sedative respiratory depression from benzodiazepines summates with HCN-induced cellular respiration inhibition; increased risk of unrecognised incipient cyanide poisoning due to sedation of early symptoms (headache, restlessness).
Nitrate (Nitroglycerin, Isosorbiddinitrat)
Nitrates are therapeutically used to induce methaemoglobin formation as a cyanide antidote — uncontrolled co-medication with cyanogenic plant preparations can, however, lead to paradoxical worsening if methaemoglobinaemia further compromises oxygen transport without medical supervision.
MAO-Hemmer (Phenelzin, Tranylcypromin)
MAO inhibitors influence amine metabolism; concurrent cyanide exposure can lead to accumulation through delayed rhodanese-mediated detoxification. Clinical evidence limited, but combination should be avoided in principle.
Thyreostatika (Carbimazol, Thiamazol/Methimazol)
HCN is partly metabolised to thiocyanate, a natural inhibitor of thyroid function; concurrent thyreostatic therapy can be aggravated to hypothyroidism — particularly with chronic sublethal exposure (e.g. frequent consumption of cyanogenic foods).
Contraindications
- Any self-administration as plant product from fresh leaves or kernels (tea, tincture, infusion, juice) — absolutely contraindicated due to fluctuating HCN content
- Chronic respiratory diseases (COPD, severe asthma) — reduced cyanide tolerance due to limited pulmonary reserve
- Known hepatic or renal insufficiency — delayed cyanide detoxification via the rhodanese system
- Anaemia and haemoglobinopathies (e.g. sickle cell anaemia) — reduced oxygen transport capacity exacerbates cellular hypoxia
- Hypothyroidism — thiocyanate as HCN metabolite aggravates hypothyroidism
- Pregnancy, lactation, children and adolescents (see above)
Harvested part: leaves and seeds
- Time of day:
- Fresh, fully developed leaves from early to mid-summer; exclusively for homeopathic or teaching/demonstration purposes. Due to the volatility of hydrocyanic acid and rapid enzymatic activity, leaves must be processed directly after cutting — drying largely destroys the active component.
- Drying:
- Gentle air drying possible, however HCN content is reduced by >90 %. Fresh processing in homeopathic or pharmaceutical facilities is customary.
- Time of day:
- Stones from ripe, black-violet drupes in late summer and early autumn; exclusively for phytochemical or forensic analysis or seed production for tree nurseries. No use as food or remedy.
- Drying:
- Drying of rinsed kernels at room temperature with ventilation; amygdalin remains stable in dry seeds for years. Storage to be labelled as toxic substance.
- PrunasinGlycosideContent: 0.5-1.5 % (Blätter / leaves)
Cyanogenic glycoside; (R)-mandelonitrile β-D-glucoside (C14H17NO6); main glycoside of cherry laurel leaves; enzymatically cleaved by β-glucosidase into glucose, benzaldehyde and hydrocyanic acid. Responsible for the bitter-almond odour of crushed leaves.
- AmygdalinGlycosideContent: 1-5 % (Samenkerne / kernels)
Cyanogenic disaccharide glycoside; biosynthetic follow-up product of prunasin via UDP-glucosyltransferase. Main glycoside of the kernels (seeds). Sequentially cleaved by amygdalin β-glucosidase first to prunasin, then by prunasin β-glucosidase to mandelonitrile, and finally by mandelonitrile lyase to benzaldehyde and HCN.
- β-Glucosidase (Prunase, Amygdalase)OtherContent: nicht quantifiziert
Plant's own enzyme complex, spatially separated from the cyanogenic glycosides; released upon tissue damage and catalyses HCN release. This two-compartment system is the biochemical basis of the plant's herbivore defence.
- Hydrogen cyanide (HCN, Blausäure)OtherContent: 0.1-0.2 % (frische Blätter, freisetzbar / fresh leaves, releasable)
Secondary toxin, released by enzymatic hydrolysis from prunasin/amygdalin. Inhibits cytochrome-c oxidase of the respiratory chain (complex IV); blocks cellular oxygen utilisation. Lethal human dose: 0.5–3.5 mg HCN/kg body weight orally, approximately 50 mg total.
- BenzaldehydEssential oilContent: nicht quantifiziert
Aromatic aldehyde, formed together with HCN during enzymatic cleavage of prunasin and amygdalin. Responsible for the characteristic bitter-almond/marzipan odour of crushed leaves — diagnostic recognition feature in suspected poisoning.
- Gerbstoffe (Catechin-Gerbstoffe)TanninContent: 1-3 %
Condensed catechin tannins in leaves and bark; astringent effect; contributing to the plant's biological activity but not relevant to toxicity.
- Flavonoide (Quercetin- und Kaempferol-Glykoside)FlavonoidContent: 0.2-0.8 %
Secondary plant substances with antioxidant properties; detected in leaves and ripe fruits; physiologically insignificant compared to HCN toxicity.
- Anthocyane (im reifen Fruchtfleisch)FlavonoidContent: nicht quantifiziert
Responsible for the black-violet colour of ripe drupes; the ripe fruit pulp itself is relatively glycoside-poor and sweetish, but the stone within is highly toxic.
- [6]MonographASPCA Animal Poison Control — Cherry (Prunus spp.)(accessed: 2026-08-10)
- [7]MonographCliniTox Giftpflanzen — Prunus laurocerasus L.: stark giftig ++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [3]BookPlants For A Future — Prunus laurocerasus(accessed: 2026-05-26)
- [4]BookMaud Grieve: A Modern Herbal — Cherry Laurel (botanical.com, 1931)(accessed: 2026-05-26)
- [1]WikipediaPrunus laurocerasus — Wikipedia (EN)(accessed: 2026-05-26)
- [2]WikipediaCherry laurel water — Wikipedia (EN)(accessed: 2026-05-26)
- [5]WikidataPrunus laurocerasus — Wikidata Q157508(accessed: 2026-05-26)