Hemlock (Conium maculatum)

While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.

Related Terms

  • Alkaloids, Apiaceae (formerly Umbelliferae) family, ash, atropine, beaver poison, California fern, carrot weed, Cicuta, conhydrine, coniceine, coniine, Conium, conium alkaloids, Conium maculate, Conium maculatum, conium ointment, conline, ethyl piperidine, fixed oil, green extract of conium, hemlock alkaloids, hemlock juice, herb bennet, juice of conium, keck, kecksies, kex, mucilage, musquash root, Nebraska fern, piperidine alkaloids, poison fool’s parsley, poison hemlock, poison parsley, poison-hemlock, pseudoconhydrine, spotted corobane, spotted hemlock, spotted parsley, succus Conii, Umbelliferae, wild carrot.

  • Note: Hemlock (Conium maculatum) is a different species from Eastern hemlock or water hemlock.

Background

  • Hemlock (Conium maculatum) is one of the most poisonous plants, due to the presence of piperidine alkaloids in all parts of the plant, including the leaves, flowers, fruits, seeds, and roots. Hemlock was purportedly the poison used in ancient Greece to execute condemned prisoners.

  • Hemlock poisoning affects the central nervous system (CNS), causing CNS stimulation followed by depression. Hemlock intoxication has occurred when this plant or parts of it are mistaken for other wild and cultivated edible plants, including fennel, wild carrot, wild chervil, anise (seeds), parsley (leaves), and parsnip (roots). Toxic reactions may result from inhalation as well as ingestion, due to the volatility of hemlock alkaloids. Drying the plant greatly reduces, but does not eliminate, the toxicity.

Scientific Evidence

Uses

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

No available studies qualify for inclusion in the evidence table.

*Key to grades:

Tradition

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

  • Antidote to poisons (strychnine), antispasmodic, arthritis, asthma, bronchitis, cancer, cramps, cystitis (acute), epilepsy (from dentition), joint pain, joint swelling, laryngeal spasm, mania (acute), narcotic, nervous excitability (motor), paralysis (agitans, early stages), Parkinson’s disease, prostate cancer, sedative, skin ailments, skin infections, teething, tetanus, tumors (indolent), ulcers, whooping cough.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

  • There is no proven safe or effective dose for hemlock in adults. Hemlock is poisonous when taken internally, except when diluted into homeopathic preparations.

Children (under 18 years old)

  • There is no proven safe or effective dose for hemlock in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid with known allergy or hypersensitivity to plants in the Apiaceae and Umbelliferae families.

Side Effects and Warnings

  • Do not ingest hemlock orally, do not inhale hemlock alkaloids, and do not use the hollow stems.

  • Hemlock poisoning affects the central nervous system (CNS), causing CNS stimulation followed by depression, including paralysis of motor nerve endings. Effects of hemlock poisoning include vomiting and nausea, trembling, movement problems, a pulse starting as slow and weak and later becoming rapid, increased respiration, salivation, urination, muscle breakdown, kidney damage or failure, convulsions, brain damage, coma, acute respiratory arrest, and death.

Pregnancy and Breastfeeding

  • Avoid when pregnant or breastfeeding due to extreme toxicity.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

  • Hemlock is poisonous when taken internally, except when diluted into homeopathic preparations. Numerous interactions are theoretically possible.

  • Hemlock may interact with agents used for the heart, drugs that are toxic to the kidneys, gastrointestinal agents, and neurologic agents.

Interactions with Herbs and Dietary Supplements

  • Hemlock is poisonous when taken internally, except when diluted into homeopathic preparations. Numerous interactions are theoretically possible.

  • Hemlock may interact with gastrointestinal herbs and supplements, herbs and supplements used for the heart, herbs and supplements that are toxic to the kidneys, and neurologic herbs and supplements.

Author Information

  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Attardo, C. and Sartori, F. Pharmacologically active plant metabolites as survival strategy products. Boll Chim Farm 2003;142(2):54-65. View Abstract
  2. Biberci, E., Altuntas, Y., Cobanoglu, A., et al. Acute respiratory arrest following hemlock (Conium maculatum) intoxication. J.Toxicol.Clin.Toxicol. 2002;40(4):517-518. View Abstract
  3. Brenet, O., Roy, P. M., Harry, P., et al. [Hemlock poisoning: an occasionally benign course]. Presse Med. 1-20-1996;25(2):82. View Abstract
  4. Carod-Artal, F. J. [Neurological syndromes linked with the intake of plants and fungi containing a toxic component (I). Neurotoxic syndromes caused by the ingestion of plants, seeds and fruits]. Rev Neurol. 5-1-2003;36(9):860-871. View Abstract
  5. Daugherty, C. G. The death of Socrates and the toxicology of hemlock. J.Med.Biogr. 1995;3(3):178-182. View Abstract
  6. Davies, M. L. and Davies, T. A. Hemlock: murder before the Lord. Med Sci Law 1994;34(4):331-333. View Abstract
  7. Drummer, O. H., Roberts, A. N., Bedford, P. J., et al. Three deaths from hemlock poisoning. Med.J.Aust. 6-5-1995;162(11):592-593. View Abstract
  8. Foster, P. F., McFadden, R., Trevino, R., et al. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876. View Abstract
  9. Frank, B. S., Michelson, W. B., Panter, K. E., et al. Ingestion of poison hemlock (Conium maculatum). West J.Med. 1995;163(6):573-574. View Abstract
  10. Gibbs, D. Dr John Andree, MD (Rheims) LRCP, founding physician of the London Hospital. J Med Biogr. 2003;11(2):87-94. View Abstract
  11. MacLaughlin, B. W., Gutsmuths, B., Pretner, E., et al. Effects of homeopathic preparations on human prostate cancer growth in cellular and animal models. Integr.Cancer Ther 2006;5(4):362-372. View Abstract
  12. Reckeweg, H. H. Materia Medica Momoeopathia Antihomotoxica, Volume I: A Selective Pharmacology. Baden-Baden: Aurelia-Verlag;1996.
  13. Reynolds, T. Hemlock alkaloids from Socrates to poison aloes. Phytochemistry 2005;66(12):1399-1406. View Abstract
  14. Thangapazham, R. L., Gaddipati, J. P., Rajeshkumar, N. V., et al. Homeopathic medicines do not alter growth and gene expression in prostate and breast cancer cells in vitro. Integr.Cancer Ther 2006;5(4):356-361. View Abstract
  15. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. View Abstract

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.