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Conium maculatum
Toxic🐾Gefleckter Schierling · (Conium maculatum)
Carrot family (Apiaceae)
Description
A red-spotted stem and an unmistakable mouse-urine smell when the leaves are crushed give poison hemlock away — a tall member of the carrot family found on damp, nitrogen-rich ground and flowering from June to August. Every part of the plant carries the piperidine alkaloid coniine, most concentrated in unripe fruit. Historically, hemlock preparations were rubbed on the skin for gout and taken internally as an antispasmodic, and in antiquity a brew of the crushed fruit famously served as a method of execution; homeopathic dilutions of the plant are still used today. None of these uses carry modern evidence of effectiveness. Poison hemlock ranks among the deadliest wild plants of the region: coniine paralyses the muscles up to respiratory arrest, and the species is easily mistaken for parsley or chervil. Foraging or handling it without expert knowledge should never be attempted.
🌿 Risk of confusion — read before wild-harvesting!
FATALLY TOXIC — ENTIRE PLANT, ESPECIALLY UNRIPE FRUITS AND ROOT. RISK OF CONFUSION with parsley, meadow chervil, anise, garden chervil — distinguishing features: red-spotted stem, hairless foliage, intense mouse-urine smell when crushed.
External use only!
This plant must NOT be taken internally. Use only as compress, salve, or bath.
CONTRAINDICATED during pregnancy
Coniine crosses the placenta and is a documented teratogen — use during pregnancy can cause congenital malformations (in particular cleft palate and limb deformities, documented in animal and porcine models) as well as ascending paralysis in the foetus. Any exposure during pregnancy is absolutely contraindicated.
CONTRAINDICATED during breastfeeding
Coniine passes into breast milk and can trigger neuromuscular paralysis in the infant. Breastfeeding: strictly contraindicated.
CONTRAINDICATED for children
Children are extremely sensitive to coniine. Even a few leaves can be fatal. Confusion poisonings with parsley or chervil are especially dangerous. No use in children and adolescents under 18 years.
Critical drug interactions with:
Nicht-depolarisierende neuromuskuläre Blocker (Rocuronium, Vecuronium, Cisatracurium) · Depolarisierende Muskelrelaxantien (Succinylcholin) · Atemdepressiva (Opioide, Benzodiazepine, Barbiturate, GABA-Agonisten)
Historical external use of hemlock ointments and oil extracts for gout, painful ulcers, tumours and inflamed lymph nodes. Already recommended in medieval herbals (15th–16th centuries) as well as by Nicholas Culpeper (1650s) for external swellings; in the 18th century promoted by the Viennese physician Anton von Störck as a 'resolving and altering' remedy. Officinal in pharmacopoeias 1864–1934. Today abandoned due to toxicity (skin absorption of coniine).
Preparation & dosage
Folk medicinal external use as compress for mastitis, malignant tumours (particularly breast), anal fissures and haemorrhoids. Widely promoted as a cancer remedy in the 18th and 19th centuries. Plants for a Future reports 'ointments and oils' for these indications. Today no longer used due to uncertain efficacy and systemic toxicity.
Preparation & dosage
Antique and medieval use as sedative and hypnotic: Dioscorides (Materia Medica, 1st cent.) and Pliny the Elder (Naturalis Historia) describe hemlock (Greek kōneion, Latin cicuta) as external analgesic and, in small amounts, as a sedative. In pharmacopoeias Conii herba was listed as a sedative — dose-dependently highly toxic.
Preparation & dosage
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 hemlock extract (Extractum Conii) as antispasmodic for tetanus, whooping cough and epileptic seizures in the 18th and 19th centuries. Coniine acts on the nicotinic acetylcholine receptor — at excessive dose ascending paralysis. Today replaced by benzodiazepines and modern anticonvulsants; pharmaceutical use obsolete.
Preparation & dosage
Homeopathic use of Conium maculatum (D6–C30), typically as constitutional remedy for glandular indurations, vertigo in the elderly, paralytic symptoms and premenstrual complaints. Pure homeopathic dilution levels (from C12) contain no pharmacologically active coniine amounts. Widespread in classical homeopathy.
Preparation & dosage
Historical-juridical use of the hemlock cup in classical Athens (5th/4th cent. BCE) as method of execution — most famous application: the execution of Socrates in 399 BCE, documented in Plato's dialogue Phaedo. Preparation from crushed unripe fruits and roots in water or wine. Plato describes the ascending paralysis from the feet upward with consciousness retained. Pure historical cultural phenomenon — no application recommendation.
Preparation & dosage
⚠ External use only
FATALLY TOXIC — ENTIRE PLANT, ESPECIALLY UNRIPE FRUITS AND ROOT. Conium maculatum contains 1.5–2 % of the piperidine alkaloid coniine plus γ-coniceine, N-methylconiine, conhydrine and pseudoconhydrine. Lethal adult dose: 0.5–1 g coniine (equivalent to 6–8 hemlock leaves). Highest concentrations in unripe fruits. Coniine acts on the nicotinic acetylcholine receptor: initial excitation, then extensive neuromuscular blockade with ascending paralysis — from feet via legs and trunk to respiratory muscles — with consciousness clearly retained. Death by respiratory paralysis. Symptoms (onset ≈ 30 min after ingestion): burning in mouth and throat, nausea, vision disturbances, inability to speak or swallow, muscle cramps, bradycardia, then paralysis. RISK OF CONFUSION with parsley, meadow chervil, anise, garden chervil — distinguishing features: red-spotted stem, hairless foliage, intense mouse-urine smell when crushed. Coniine degrades only slowly on drying. Skin absorption also possible. In case of suspected poisoning: IMMEDIATELY call emergency services and poison control. No self-medication. No lay use. ASPCA classification (accessed 2026-08-10): toxic to dogs and cats.
⏱ Max continuous use: 1 weeks
Coniine crosses the placenta and is a documented teratogen — use during pregnancy can cause congenital malformations (in particular cleft palate and limb deformities, documented in animal and porcine models) as well as ascending paralysis in the foetus. Any exposure during pregnancy is absolutely contraindicated.
Coniine passes into breast milk and can trigger neuromuscular paralysis in the infant. Breastfeeding: strictly contraindicated.
Children are extremely sensitive to coniine. Even a few leaves can be fatal. Confusion poisonings with parsley or chervil are especially dangerous. No use in children and adolescents under 18 years.
Drug interactions
Nicht-depolarisierende neuromuskuläre Blocker (Rocuronium, Vecuronium, Cisatracurium)
Coniine blocks nicotinic acetylcholine receptors at the motor end-plate; additive neuromuscular blockade with prolonged postoperative paralysis and risk of respiratory arrest.
Depolarisierende Muskelrelaxantien (Succinylcholin)
Coniine modulates the same nicotinic receptors; unpredictable additive effect, prolonged apnoea, malignant-hyperthermia-like picture possible.
Atemdepressiva (Opioide, Benzodiazepine, Barbiturate, GABA-Agonisten)
Additive respiratory depression through combination of central sedation with nicotinic blockade of respiratory muscles — risk of lethal respiratory arrest.
Cholinesterase-Hemmer (Neostigmin, Pyridostigmin, Donepezil, Rivastigmin)
Increased acetylcholine levels may initially partially antagonize coniine effects but paradoxically intensify paralysis through receptor desensitization; unpredictable pharmacodynamics.
Nikotin und nikotinerge Substanzen (Vareniclin, Nikotinkaugummi, Tabak)
Competition and cross-sensitivity at the nicotinic receptor; unclear modulation of toxic threshold, especially in heavy smokers or those on varenicline.
Contraindications
- Myasthenia gravis and neuromuscular disorders — coniine dramatically intensifies neuromuscular blockade
- Respiratory diseases (COPD, severe asthma, sleep apnoea) — risk of respiratory depression from nicotinic blockade
- Bradycardia and AV block — coniine intensifies bradyarrhythmias
- Hepatic and renal insufficiency — delayed elimination of alkaloids
- Planned surgery with muscle relaxation in the next 4 weeks — interaction with anaesthetics
- Pregnancy, breastfeeding, children and adolescents (see above)
Harvested part: whole plant
- Time of day:
- Late morning during early fruit formation — highest alkaloid content before fruit ripening
- Drying:
- Dry at 40–50 °C in the shade; coniine is relatively volatile but not completely volatile — even dried material remains toxic. PROTECTIVE GLOVES MANDATORY — coniine is absorbed through the skin. Harvest exclusively by trained botanists or pharmacists.
- Time of day:
- Daytime when split fruits are still unripe and green — coniine content up to 3.5 % at unripe stage
- Drying:
- Schizocarp fruits (mericarps) gently dried at 30–40 °C; highest toxicity — the historical 'hemlock cup' used unripe fruits. EXCLUSIVELY for research or pharmaceutical purposes under strict safety equipment.
- Coniine (2-Propylpiperidin)AlkaloidContent: 1.5-2 % (gesamtes Kraut), bis 3,5 % in unreifen Früchten
Main alkaloid of poison hemlock; simple piperidine alkaloid (not indole/tropane); competitive antagonist and desensitizer at the nicotinic acetylcholine receptor (nAChR) of the motor end-plate and in autonomic ganglia. Causes ascending paralysis with retained consciousness. First alkaloid with established chemical structure (1881) and first chemically synthesized alkaloid (1886).
- γ-Coniceine (gamma-Coniceine)AlkaloidContent: variabel, hoch in jungen Pflanzen
Biosynthetic precursor of all hemlock alkaloids; unsaturated imine (dihydropyridine-like); ≈ 7–8× more toxic than coniine itself; enzymatically reduced to coniine during fruit ripening. Classic example of a more toxic biosynthetic intermediate.
- N-MethylconiineAlkaloidContent: < 0.5 %
Methyl derivative of coniine; formed by N-methylation in the plant; approximately 3× more toxic than coniine; same mechanism of action at the nicotinic acetylcholine receptor.
- ConhydrineAlkaloidContent: < 0.3 %
Hydroxylated piperidine alkaloid; lower toxicity than coniine; contributes to overall toxicity. Stereochemically related to pseudoconhydrine.
- PseudoconhydrineAlkaloidContent: < 0.3 %
Stereoisomer of conhydrine; lower pharmacological activity; detectable in all plant parts; together with coniine used as chemotaxonomic marker of the genus Conium.
- Ätherisches Öl (mausartig riechende Komponenten)Essential oilContent: Spuren
Volatile components produce the characteristic mouse-urine smell when the plant is crushed — important botanical identification feature to distinguish from parsley, chervil and anise. Does not contribute primarily to toxicity.
- Flavonoide (Quercetin- und Kaempferol-Glykoside, Diosmin)FlavonoidContent: nicht quantifiziert
Antioxidant accompanying substances in leaves and stems; without primary role in toxicology; detected in several phytochemical analyses.
- Cumarine (Bergapten, Xanthotoxin Spuren)OtherContent: Spuren
Furanocoumarins in small amounts; can theoretically intensify phototoxic skin reactions; of minor significance compared with coniine toxicity.
- [5]MonographThe killer of Socrates: Coniine and Related Alkaloids in the Plant Kingdom(accessed: 2026-05-26)
- [6]MonographDeath of Socrates: a likely case of poison hemlock (Conium maculatum) poisoning(accessed: 2026-05-26)
- [7]MonographASPCA Animal Poison Control — Poison Hemlock (Conium maculatum)(accessed: 2026-08-10)
- [8]MonographCliniTox Giftpflanzen — Conium maculatum L.: sehr stark giftig +++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [4]BookPlants for a Future — Conium maculatum(accessed: 2026-05-26)
- [1]WikipediaConium maculatum — Wikipedia (EN)(accessed: 2026-05-26)
- [2]WikipediaGefleckter Schierling — Wikipedia (DE)(accessed: 2026-05-26)
- [3]WikidataConium maculatum — Wikidata Q156631(accessed: 2026-05-26)