Herb & supplement monograph

Hemlock Drug Interactions, Uses, Safety & More

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Interaction report

Drugs that interact with Hemlock

0 medications have a known interaction with Hemlock, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for Hemlock. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Hemlock combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Hemlock: Uses, Safety & Side Effects

The bottom line

Hemlock (Conium maculatum) is a highly poisonous plant that has no safe or proven medicinal use today. Even small amounts can cause paralysis and death, so it should never be consumed or applied to the body. Do not use hemlock or any product containing it.

Scientific name
Conium maculatum
Family
Apiaceae
Part used
Whole plant, including leaves, seeds, stems, and roots (all parts are poisonous)
Common forms
Not safely used in any form; historically prepared as extracts, tinctures, or poultices
People commonly use it for
  • Historical sedative or pain reliever
  • Traditional treatment for muscle spasms
  • Folk use for joint and nerve pain
  • Historical execution poison
  • Homeopathic preparations

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallBest avoided

Hemlock is a deadly poison and should never be taken in any amount.

PregnancyUnsafe

When used orally because ingestion can be lethal; avoid using.

Read the full pregnancy detail
BreastfeedingUnsafe

When used orally because ingestion can be lethal; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Hemlock (Conium maculatum) is a tall, flowering plant in the carrot family (Apiaceae). It is sometimes called poison hemlock. It grows widely across Europe, North America, and other temperate regions, often along roadsides, ditches, and in damp fields. The plant has feathery, fern-like leaves, small white flowers in umbrella-shaped clusters, and purple or red spots on its smooth, hollow stems.

Despite its long history in folk medicine and its infamous use as a poison in ancient times (it is widely believed to have killed the philosopher Socrates), hemlock is extremely toxic. It is not sold or recommended as a dietary supplement. Any historical medicinal use has been abandoned because of how dangerous it is. We include this monograph mainly to warn people about its dangers and to help with accidental poisoning awareness.

Uses & effectiveness

In the past, hemlock was occasionally used as a sedative, a pain reliever, or a treatment for muscle spasms and conditions like Parkinson-type tremors. These uses were based on tradition, not on solid science.

There is no reliable modern evidence that hemlock safely treats any condition. The plant's toxic effects far outweigh any possible benefit, and there is no safe dose. Because of its deadly nature, it has been removed from medical practice. Some extremely diluted homeopathic products list it as an ingredient, but standard homeopathy contains little or no measurable plant material, and there is no good evidence it works.

Bottom line: hemlock should not be used to treat anything. Safer, proven options exist for every condition it was once used for.

How it works

Hemlock contains a group of poisonous compounds called piperidine alkaloids, the best known being coniine and gamma-coniceine. These chemicals act on the nervous system.

Coniine affects nicotinic receptors at the junctions between nerves and muscles. At first it may overstimulate them, but it quickly causes them to stop working. This leads to progressive muscle weakness and paralysis. When the muscles used for breathing become paralyzed, a person can die from respiratory failure while remaining conscious. These effects are well documented from poisoning cases and laboratory study, not from controlled treatment research.

Safety & precautions

Hemlock is one of the most poisonous plants in the world. Every part of the plant — leaves, stems, seeds, flowers, and roots — is toxic. Poisoning can happen by eating it, and toxins may also be absorbed through the skin or breathed in when the plant is handled or burned.

Hemlock is easily mistaken for edible plants like wild carrot (Queen Anne's lace), wild parsnip, parsley, or fennel. Many accidental poisonings happen when foragers confuse it with these plants. Never forage or eat any wild plant you cannot identify with certainty.

Pregnancy and breastfeeding: Hemlock must be avoided completely. It is a known poison and has caused birth defects in animals. Its toxins can harm a developing baby or pass into breast milk.

If you suspect hemlock poisoning in a person, pet, or livestock, call emergency services or a poison control center immediately. In the United States, you can reach Poison Control at 1-800-222-1222.

Side effects

Hemlock does not cause mild "side effects" — it causes serious poisoning. Symptoms can begin within an hour of exposure and may include:

  • Burning in the mouth and throat, nausea, vomiting, and drooling
  • Dizziness, trembling, and confusion
  • Widening of the pupils
  • Rapid then slowing heartbeat
  • Progressive muscle weakness and paralysis
  • Seizures
  • Difficulty breathing leading to respiratory failure and death

There is no specific antidote for hemlock poisoning. Treatment is supportive and given in a hospital, and may include breathing support. Skin contact with the plant sap can also cause irritation in some people.

Hemlock: Reported Adverse Effects

Documented safety reports on Hemlock from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Hemlock is generally regarded as unsafe for use. Any benefits of therapy may not outweigh the risk of toxicity. Orally, hemlock can cause burning of the mouth, throat, and abdomen, nausea, vomiting, excessive urination, salivation, drowsiness, mydriasis, muscle pain, rapid muscle swelling and stiffness, rhabdomyolysis, and tachycardia followed by bradycardia. It can also cause loss of speech, paralysis, encephalopathy, unconsciousness, rapid respiration and respiratory arrest, cardiovascular collapse, renal toxicity, and death.

  1. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3.
  2. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  3. Biberci, E., Altuntas, Y., Cobanoglu, A., and Alpinar, A. Acute respiratory arrest following hemlock (Conium maculatum) intoxication. J.Toxicol.Clin.Toxicol. 2002;40(4):517-518.
  4. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876.
  5. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382.
  6. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr
  7. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Bruno, S., Scatizzi, A., and De Marco, S. Rhabdomyolysis and acute tubular necrosis in coniine (hemlock) poisoning. Lancet 12-16-1989;2(8677):1461-1462.
  8. Rizzi, D., Introna, F., Jr., Gagliano, Candela R., Di Nunno, C., Ricco, R., Recchia, R., and De, Michele, V. [Toxic rhabdomyolysis and tubular necrosis in hemlock poisoning. 4 case reports]. Clin.Ter. 2-15-1988;124(3):193-201.
  9. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6.
  10. Chen HY, Horng H, Rowley F, Smollin C. Rapid respiratory arrest after ingestion of poison hemlock mistaken for wild celery. Clin Toxicol (Phila). 2017;55(2):155-156.
Reports by condition
Cardiac arrest Cardiovascular

Orally, hemlock can cause tachycardia followed by bradycardia, cardiovascular collapse, and death. In one case report, a 6-year old girl had prolonged coagulation tests after accidental ingestion of hemlock. It can also cause hypertension.

Intravenously, hemlock resulted in a brief cardiac arrest followed by return of spontaneous circulation in one case report.

  1. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3.
  2. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  3. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382.
  4. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6.
  5. Boskabadi J, Askari Z, Zakariaei Z, Fakhar M, Tabaripour R. Mild-to-severe poisoning due to Conium maculatum as toxic herb: A case series. Clin Case Rep. 2021 Jul 23;9(7):e04509.
  6. Brtalik D, Stopyra J, Hannum J. Intravenous poison hemlock injection resulting in prolonged respiratory failure and encephalopathy. J Med Toxicol. 2017;13(2):180-182.
Epilepsy Neurologic/CNS

Orally, hemlock can cause drowsiness, fatigue, lethargy, dizziness, numbness, loss of speech, tremors, paralysis, seizures, encephalopathy, unconsciousness, and death. Death from hemlock toxicity is usually due to respiratory paralysis.

A case report describes prolonged status epilepticus in a 41-year-old, previously healthy female who mistook hemlock root for parsnip. She developed severe vomiting and drowsiness, followed by prolonged status epilepticus which was refractory to multiple drugs. Seizures and the abnormal electroencephalogram were ultimately controlled with thiopental, gradually weaning to long-term oral treatment with lacosamide and perampanel, which returned the patient to her baseline level of functioning.

  1. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3.
  2. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  3. Carod-Artal FJ. [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 2003;36:860-71.
  4. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876.
  5. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382.
  6. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr
  7. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6.
  8. Boskabadi J, Askari Z, Zakariaei Z, Fakhar M, Tabaripour R. Mild-to-severe poisoning due to Conium maculatum as toxic herb: A case series. Clin Case Rep. 2021 Jul 23;9(7):e04509.
  9. Hove KD, Brøns C, Færch K, Lund SS, Rossing P, Vaag A. Effects of 12 weeks of treatment with fermented milk on blood pressure, glucose metabolism and markers of cardiovascular risk in patients with type 2 diabetes: a randomised double-blind placebo-contro
  10. Parreira S, Antunes AP, Bento H, Moniz I. A hemlock salad: a case report of super-refractory status epilepticus after accidental hemlock ingestion. Neurol Sci. 2021 Oct;42(10):4335-9.
Muscle breakdown Musculoskeletal

Orally, hemlock can cause muscle pain, rapid muscle swelling and stiffness, and rhabdomyolysis. Plasma exchange effectively improved the signs of rhabdomyolysis in one case of hemlock poisoning.

  1. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3.
  2. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  3. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382.
  4. Boskabadi J, Askari Z, Zakariaei Z, Fakhar M, Tabaripour R. Mild-to-severe poisoning due to Conium maculatum as toxic herb: A case series. Clin Case Rep. 2021 Jul 23;9(7):e04509.
  5. Montemurro, N. E., Di Maggio, A., Strippoli, P., Coviello, F., Godino, F., Miloro, G., and Scatizzi, A. Combined dialysis and plasma-exchange in acute renal failure. Biomater.Artif.Cells Immobilization Biotechnol. 1993;21(2):283-287.
Nausea and vomiting Gastrointestinal
Poisoning Renal
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no safe dose of hemlock. It is not a supplement and should never be measured out or taken. Even a small amount of plant material or seeds can be fatal to humans and animals.

Do not buy, prepare, or consume any product that contains Conium maculatum. If you come across a supplement or remedy claiming to contain hemlock, do not use it, and speak with a pharmacist or doctor about safer, proven alternatives.

Pregnancy & Breastfeeding
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 18 references that drive our Hemlock monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Lopez TA, Cid MS, Bianchini ML. Biochemistry of hemlock (Conium maculatum L.) alkaloids and their acute and chronic toxicity in livestock. A review. Toxicon 1999;37:841-65. PubMed
  2. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3. PubMed
  3. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  4. Carod-Artal FJ. [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 2003;36:860-71.
  5. Biberci, E., Altuntas, Y., Cobanoglu, A., and Alpinar, A. Acute respiratory arrest following hemlock (Conium maculatum) intoxication. J.Toxicol.Clin.Toxicol. 2002;40(4):517-518.
  6. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876. PubMed
  7. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. PubMed
  8. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
  9. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Bruno, S., Scatizzi, A., and De Marco, S. Rhabdomyolysis and acute tubular necrosis in coniine (hemlock) poisoning. Lancet 12-16-1989;2(8677):1461-1462. PubMed
  10. Rizzi, D., Introna, F., Jr., Gagliano, Candela R., Di Nunno, C., Ricco, R., Recchia, R., and De, Michele, V. [Toxic rhabdomyolysis and tubular necrosis in hemlock poisoning. 4 case reports]. Clin.Ter. 2-15-1988;124(3):193-201.
  11. Montemurro, N. E., Di Maggio, A., Strippoli, P., Coviello, F., Godino, F., Miloro, G., and Scatizzi, A. Combined dialysis and plasma-exchange in acute renal failure. Biomater.Artif.Cells Immobilization Biotechnol. 1993;21(2):283-287. PubMed
  12. Scatizzi, A., Di Maggio, A., Rizzi, D., Sebastio, A. M., and Basile, C. Acute renal failure due to tubular necrosis caused by wildfowl-mediated hemlock poisoning. Ren Fail. 1993;15(1):93-96. PubMed
  13. Brtalik D, Stopyra J, Hannum J. Intravenous poison hemlock injection resulting in prolonged respiratory failure and encephalopathy. J Med Toxicol. 2017;13(2):180-182. PubMed
  14. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6. DOI
  15. Chen HY, Horng H, Rowley F, Smollin C. Rapid respiratory arrest after ingestion of poison hemlock mistaken for wild celery. Clin Toxicol (Phila). 2017;55(2):155-156. PubMed
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Pharmacist Counseling Corner

Hemlock: Common Questions

Does Hemlock interact with prescription medications?
We do not currently list any known drug interactions for Hemlock. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Hemlock interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Hemlock with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Hemlock interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
Is Hemlock safe to take as a supplement?
No. Hemlock is a deadly poison with no safe dose. It should never be taken as a supplement or remedy.
What happens if you eat Hemlock?
Eating Hemlock can cause vomiting, muscle weakness, paralysis, and death from respiratory failure, sometimes within hours. Seek emergency care right away if exposure is suspected.
How can I tell Hemlock apart from edible plants?
Poison Hemlock looks similar to wild carrot, parsley, and fennel, but it has smooth hollow stems with purple or red spots and an unpleasant smell. Because mistakes can be fatal, never eat a wild plant unless an expert has confirmed it is safe.
Is Hemlock the same as the Hemlock tree?
No. The poisonous plant Conium maculatum is unrelated to Hemlock trees (Tsuga), which are evergreen conifers. The shared name causes confusion, but they are entirely different plants.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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