Related Terms

• Apiaceae (family), bulblet-bearing water hemlock, Cicuta, Cicuta bulbifera, Cicuta douglasii, Cicuta maculata, Cicuta virosa, cicutoxin, cowbane, fool's parsley, northern water hemlock, spotted water hemlock, water hemlock, western water hemlock.

• Note: Several accidental poisonings have been reported due to confusion of water hemlock roots with turnip, parsnip, or wild carrot. Water hemlock (Cicuta spp.) should not be confused with poison hemlock (Conium spp.), although the species have similar common names and similar general appearance.

Background

• Water hemlock grows in temperate wet, marshy areas in mainly North America. According to the U. S. Department of Agriculture (USDA), "water hemlock is the most violently toxic plant that grows in North America."

• Water hemlock is sometimes mistaken for parsnips, due to the similar appearance of their white tuberous roots.

• Although water hemlock was rarely used for headache according to traditional use, there is insufficient available evidence in humans or animals to support the use of water hemlock for any indication.

Scientific Evidence

Tradition/Theory

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.

• Headache.

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):

• Avoid in all patients as water hemlock is highly toxic and may lead to death.

Children (younger than 18 years):

• Avoid in all patients as water hemlock is highly toxic and may lead to death.

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 in individuals with a known allergy or hypersensitivity to water hemlock (Cicuta spp.) or its constituents.

Side Effects and Warnings

• Avoid water hemlock as it is highly toxic and may cause vomiting, acute renal (kidney) failure, marked metabolic acidosis (acidic blood), drowsiness, seizures and convulsions, or unconsciousness that may lead to death.

• Taking water hemlock by mouth may cause an explosive illness with orthostatic hypotension (decreased blood pressure upon standing) or tachycardia (increased heartbeat). It may also cause dilated pupils, discoloration of the skin due a lack of oxygen in the blood, and a breakdown of skeletal muscle due to injury.

Pregnancy and Breastfeeding

• Avoid if pregnant or breastfeeding as water hemlock is highly toxic and may lead to death.

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

• Taking water hemlock by mouth may cause an explosive illness with seizures and convulsions that may lead to death. Caution is advised when combining water hemlock with anticonvulsive agents, or agents that may lower seizure threshold.

• Taking water hemlock by mouth may cause orthostatic hypotension (decreased blood pressure upon standing) or tachycardia (increased heartbeat). In theory, water hemlock may interact with other cardiac (heart) agents.

• Water hemlock may also cause rhabdomyolysis (breakdown of skeletal muscle due to injury), marked metabolic acidosis (acidic blood), or acute renal (kidney) failure. Based on these effects, caution is advised when taking water hemlock with agents that are excreted through the kidneys.

• Water hemlock may also interact with sedatives, as neurologic lethargy (drowsiness), or unconsciousness that may lead to death has been reported.

Interactions with Herbs and Dietary Supplements

• Taking water hemlock by mouth may cause an explosive illness with seizures and convulsions that may lead to death. Caution is advised when combining water hemlock with herbs that have anticonvulsive effects, or herbs that may lower seizure threshold.

• Taking water hemlock by mouth may cause orthostatic hypotension (decreased blood pressure upon standing) or tachycardia (increased heartbeat). In theory, water hemlock may interact with other herbs or supplements with potential cardiac (heart) effects.

• Water hemlock may also cause rhabdomyolysis (breakdown of skeletal muscle due to injury), marked metabolic acidosis (acidic blood), or acute renal (kidney) failure. Based on these effects, caution is advised when taking water hemlock with agents that are excreted through the kidneys.

• Water hemlock may also interact with sedatives, as neurologic lethargy (drowsiness), or unconsciousness that may lead to death has been reported.

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. Applefeld JJ, Caplan ES. A case of water hemlock poisoning. JACEP. 1979;8(10):401-403. View Abstract

2. Carlton BE, Tufts E, Girard DE. Water hemlock poisoning complicated by rhabdomyolysis and renal failure. Clin.Toxicol. 1979;14(1):87-92. View Abstract

3. From the Centers for Disease Control and Prevention. Water hemlock poisoning--Maine, 1992. JAMA 5-18-1994;271(19):1475. View Abstract

4. Haupt H. [Poisonous and less poisonous plants. Conium maculatum and Cicuta virosa]. Kinderkrankenschwester. 2003;22(11):495-496. View Abstract

5. Heath KB. A fatal case of apparent water hemlock poisoning. Vet.Hum.Toxicol. 2001;43(1):35-36. View Abstract

6. Knutsen OH. Paszkowski P. New aspects in the treatment of water hemlock poisoning. J.Toxicol.Clin.Toxicol. 1984;22(2):157-166. View Abstract

7. Koloshtivina OV. [Poisonings of children by water hemlock]. Med.Sestra. 1980;39(10):37-38. View Abstract

8. Landers D, Seppi K, Blauer W. Seizures and death on a white river float trip. Report of water hemlock poisoning. West J.Med. 1985;142(5):637-640. View Abstract

9. Lkhagvazhav Kh, Biambasuren Ch, Maslov AV. [Group poisoning by water hemlock]. Sud.Med.Ekspert. 1980;23(3):51-52. View Abstract

10. Mack RB. Keats, Socrates and fool's parsley--water hemlock poisoning. N.C.Med.J. 1985;46(3):163-164. View Abstract

11. Muratova LM. [Providing aid before the hospital stage to children with water hemlock poisoning]. Feldsher.Akush. 1981;46(5):38-40. View Abstract

12. Rizzi D, Basile C, Di Maggio A, et al. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephrol.Dial.Transplant. 1991;6(12):939-943. View Abstract

13. Short J. Water hemlock poisoning. Emerg.Nurse 2006;14(7):18-19. View Abstract

14. van Heijst AN, Pikaar SA, van Kesteren RG, et al. [Poisoning due to water hemlock (Cicuta virosa)]. Ned.Tijdschr.Geneeskd. 12-31-1983;127(53):2411-2413. View Abstract

15. Water hemlock poisoning--Maine, 1992. MMWR Morb.Mortal.Wkly.Rep. 4-8-1994;43(13):229-231. View Abstract