What Are Abortion Plants and Why Are They Dangerous?

Abortion plants are species that have historically been consumed or applied to induce miscarriage or prevent pregnancy, and they are dangerous because the compounds responsible for those effects are often the same ones that poison the liver, kidneys, and nervous system of the person taking them. Dozens of plant species across many cultures have been documented as traditional abortifacients, with one review of Persian medical texts alone identifying 88 such plants.¹ The core problem is that the “dose” needed to end a pregnancy and the dose that causes organ failure or death are uncomfortably close together, and in many cases they overlap entirely.

What Counts as an Abortion Plant

The term covers any plant whose leaves, roots, seeds, essential oils, or extracts have been used to terminate a pregnancy. In traditional medicine systems, these plants fall into overlapping categories. Some are classified as emmenagogues, meaning they stimulate menstrual flow and were taken when a period was late. Others are outright abortifacients, intended to cause uterine contractions strong enough to expel a developing embryo or fetus. Still others were used after an incomplete miscarriage to help expel retained tissue. Ancient Persian medical texts, for instance, distinguished between plants that induced abortion, plants that extracted a dead fetus, and plants that expelled the placenta.¹

These plants are not a fringe curiosity. Researchers analyzing six herbal formulations from ancient Persia found they contained 39 different species spanning 21 plant families.² Similar traditions existed across Europe, the Americas, sub-Saharan Africa, and South and East Asia. The plants most commonly referenced in both historical records and modern poisoning reports include pennyroyal, tansy, rue, savin juniper, and various species containing ergot alkaloids. Each works through a different mechanism, and each carries a distinct toxicity profile.

Pennyroyal and Liver Failure

Pennyroyal (Mentha pulegium) is probably the most widely discussed abortion plant in the English-speaking world, partly because pennyroyal tea was sold openly in health-food stores for decades before its dangers became broadly recognized. The plant’s essential oil contains a compound called pulegone, which the liver converts into toxic byproducts, including one called menthofuran. These metabolites overwhelm the liver’s built-in defenses in a process that mirrors acetaminophen overdose: the body’s protective stores of glutathione get used up, and once they are gone, liver cells start dying.³

What makes pennyroyal particularly treacherous is the delay. A person might drink the oil or a concentrated tea and feel relatively fine for a day or two, then suddenly deteriorate as liver failure sets in. Case reports describe progression to total liver shutdown and death. As little as 10 milliliters of pennyroyal oil has been linked to moderate to severe liver damage.³ That is roughly two teaspoons. The margin between a dose someone might consider “medicinal” and a dose that destroys the liver is vanishingly small, and animal research has confirmed that the toxic intermediates are created by the liver’s own processing enzymes.⁴

Tansy, Thujone, and the Nervous System

Tansy (Tanacetum vulgare) is another plant with a long history as a folk abortifacient, commonly prepared as a tea or tincture across Europe. Its primary toxic compound is thujone, a molecule that also appears in wormwood (the herb behind absinthe), sage, and cedar. Thujone targets the nervous system rather than the liver. It interferes with a receptor in the brain that normally calms neural activity, and the result can be seizures, confusion, and loss of consciousness.⁵

Clinical poisoning cases from commercial essential oils of sage, thuja, and cedar have documented violent seizures as the primary symptom.⁶ Thujone comes in two forms, and one is roughly two to three times more potent than the other as a neurotoxin, which means the danger of any given batch of tansy tea depends heavily on the plant’s chemistry, something the person drinking it has no way to assess.⁵ Researchers have also cautioned that the toxicity of these essential oils should not be attributed to thujone alone; the oils contain hundreds of constituents, many of which contribute to the overall danger.⁷

Rue and Organ Damage

Rue (Ruta graveolens) remains widely used in parts of South America and Southern Europe as a folk remedy for unwanted pregnancy, often brewed into a strong tea or mixed with other herbs. Data from a South American poison center found that people who took rue, either alone or combined with other plants for self-managed abortions, showed higher rates of liver, kidney, and blood-related problems compared to other poisoning cases.⁸

Severe cases have involved multi-organ failure requiring emergency measures including dialysis. The organ damage is thought to be caused by coumarin-type compounds found in the plant, though the exact mechanism is still not fully understood. Rue also carries a separate and unusual risk: it contains psoralen, a substance that binds to DNA in skin cells and reacts with ultraviolet light. People who handle or ingest rue and then go into sunlight can develop a painful skin reaction on any exposed area, a condition known as photodermatitis.⁸

Savin Juniper and Implantation

Savin juniper (Juniperus sabina) has one of the longest histories as an abortion plant in European folk medicine. Its essential oil contains around 50% sabinyl acetate, which animal studies have shown can prevent a fertilized embryo from implanting in the uterine wall. In mouse experiments, the oil and the isolated sabinyl acetate both prevented pregnancy in about half the animals when administered during the implantation window. When given later in pregnancy, during the period when organs are forming, the same oil did not cause malformations or terminate pregnancy.⁹

Why Dosing Is Essentially Impossible

One of the fundamental reasons abortion plants are so dangerous is that there is no reliable way to control the dose. The concentration of active and toxic compounds in any given plant varies depending on the part used, the growing conditions, the time of harvest, and how it was stored or prepared.10 Two cups of pennyroyal tea brewed from different batches of the same plant species could deliver wildly different amounts of pulegone. Two bundles of tansy harvested a week apart from the same field could have different thujone profiles.

This variability is not a minor footnote. It is the reason that folk traditions around these plants are so contradictory: some historical accounts describe a plant as a mild menstrual regulator, while others describe the same plant as a deadly poison. Both accounts can be accurate because both outcomes are possible depending on the batch. Modern pharmaceutical abortifacients like mifepristone are manufactured to exact specifications, with each pill containing a known quantity of a single well-studied compound. A person drinking a herbal decoction has no equivalent guarantee. Essential oils concentrated from the same species can vary in their key toxic constituents by a factor of several times, and the person consuming them has no analytical chemistry lab in their kitchen.

Risks to the Fetus When Abortion Fails

Not every attempt to end a pregnancy with herbal abortifacients succeeds. When the plant fails to cause a miscarriage but exposes the developing fetus to its toxic compounds, the consequences can be severe. A systematic review encompassing nearly 40,000 study participants found that some medicinal plants could cause developmental abnormalities or fetal death, particularly in the first trimester, because the active ingredients of certain plants can cross the placental barrier and reach the fetus directly.¹¹

The concern extends beyond intentional use. Essential oil constituents such as camphor, thujone, pulegone, and others have documented reproductive toxicity including teratogenic effects, meaning they can cause birth defects.¹² A pregnant person who takes an herbal abortifacient and does not miscarry may continue the pregnancy unaware that the fetus has been exposed to compounds capable of disrupting organ development. This is one of the less-discussed but genuinely worrying aspects of herbal abortifacient use.

Real-World Clinical Consequences

The dangers described above are not theoretical. Emergency departments and poison centers, particularly in regions where access to safe abortion is restricted, continue to see patients who have taken herbal abortifacients. A case series from northern Uganda documented two women who used common local plants, wandering jew (Commelina africana) and bitter leaf (Vernonia amygdalina), to induce abortions. One developed uterine necrosis, meaning the tissue of her uterus died, leading to pelvic infection that required multiple surgeries and powerful antibiotics. The other developed acute liver and kidney failure and died.¹³

These cases illustrate something important: the plants involved were not exotic or obscure. They were common species that people in the region encountered regularly and may have thought of as relatively mild. The severity of the outcomes, organ death, systemic infection, and fatal organ failure, would have been difficult to predict from the plants’ everyday appearance as unremarkable weeds or garden herbs.

Ergot and the Line Between Medicine and Poison

The history of ergot offers a useful lens for understanding how abortion plants sit on the boundary between remedy and toxin. Ergot is not technically a plant but a fungus (Claviceps purpurea) that infects grain, particularly rye. For centuries, people who ate bread made from contaminated flour suffered mass poisonings that included miscarriages, convulsions, and gangrene. Eventually, practitioners realized the same alkaloids that caused mass poisoning could be directed at the uterus on purpose.¹⁴

By the 19th century, ergot was being used medically to control uterine bleeding and to manage irregular contractions after delivery. But its use to induce abortion was always fraught with danger because the ergot alkaloids constrict blood vessels throughout the body, not just in the uterus. The transition from “folk abortifacient” to “pharmaceutical tool” only happened once chemists isolated the specific alkaloids responsible for uterine contractions and figured out how to dose them precisely. The crude plant material was simply too unpredictable, a pattern that repeats across virtually every abortion plant ever used.

The Livestock Connection

Humans are not the only species affected by these plants. Ranchers and veterinarians have long known that certain range plants cause spontaneous abortions in cattle, sheep, and other livestock. Ponderosa pine needles are a well-documented example: feeding roughly six pounds of freshly ground pine needles daily to cattle starting late in pregnancy consistently induced abortion within about a week, apparently by reducing blood flow through the placenta and starving the fetus of oxygen.¹⁵

The veterinary research is relevant to understanding human risk for a couple of reasons. First, it confirms that plants in normal environments, not just tropical exotics or rare herbs, can contain potent abortifacient compounds. Ponderosa pines grow across enormous swaths of North America and are not something most people would associate with reproductive danger. Second, the veterinary work shows that the mechanism of action varies widely between species of plant: some cut off blood supply, some trigger uterine contractions, some poison the embryo directly. There is no single “abortion plant mechanism,” which makes the whole category harder to predict and harder to treat when something goes wrong.

The Silphium Mystery

Any discussion of abortion plants eventually arrives at silphium, a plant from ancient Cyrenaica (modern-day Libya) that was so valued as a contraceptive and abortifacient that it may have been harvested into extinction. Ancient Greek and Roman texts describe it as extraordinarily effective, and its image appeared on coins from the region. The traditional explanation for its disappearance has been straightforward: demand outstripped supply, and people harvested it until none was left.¹⁶

More recent research has complicated that story. An analysis of ancient climate data suggests that human-driven environmental change, not just direct harvesting, may have been the dominant factor in silphium’s extinction. If correct, this would make silphium one of the earliest recorded cases of a species wiped out by climate change caused by human activity.¹⁷ We will never know for certain how effective silphium actually was, since we cannot study a plant that no longer exists. But its story captures something true about the broader category: people have always wanted reliable reproductive control, and for most of history, the plant kingdom was the only pharmacy available. The results were inconsistent at best and fatal at worst.

Herb-Drug Interactions and Hidden Exposure

A less obvious danger arises when someone takes herbal preparations alongside prescription or over-the-counter medications. Many of the compounds in abortifacient plants are processed by the same liver enzymes that metabolize common drugs. When these overlap, the herbal compound can either amplify or blunt the drug’s effect, or the drug can accelerate the conversion of a plant compound into its toxic form. The variability in bioactive substances between batches of the same herb makes these interactions even harder to predict.¹⁰

Pennyroyal’s liver toxicity, for example, follows a pathway similar to acetaminophen poisoning. A person who has taken acetaminophen recently and then drinks pennyroyal tea is depleting the same glutathione stores from two directions simultaneously, potentially accelerating liver failure beyond what either substance would cause alone. This kind of interaction is rarely discussed in folk medicine traditions because the concept of shared metabolic pathways was not understood when these traditions developed. It remains under-recognized today, particularly among people who view herbal products as inherently gentle or “natural” and therefore unlikely to interact with pharmaceuticals.

Why People Still Turn to These Plants

Given the documented lethality and unpredictability, a reasonable question is why anyone would still use herbal abortifacients. The answer is almost entirely about access. In regions where safe abortion services are legally restricted, economically out of reach, or geographically distant, traditional plant-based methods persist because they are available and familiar. The case series from northern Uganda described earlier involved plants that grew locally and cost nothing, used by women who had limited or no access to clinical care.¹³ The same dynamic plays out across parts of South America, South Asia, and sub-Saharan Africa.

Even in wealthier countries, interest in herbal abortifacients tends to rise when legal access to clinical options narrows. Online forums and social media periodically circulate recipes for pennyroyal tea, tansy infusions, or concentrated rue. The information shared is often incomplete, omitting or downplaying the liver failure, seizures, and kidney damage documented in the medical literature. The framing of these plants as traditional, natural, or time-tested lends them a credibility they do not deserve at the doses required to affect a pregnancy. A compound does not become safer because it comes from a leaf rather than a laboratory; it simply becomes harder to dose.

1
Jundishapur Journal of Natural Pharmaceutical Products. Medicinal Plants with Abortifacient or Emmenagogue Activity: A Narrative Review Based on Traditional Persian Medicine
2
PubMed. An analysis of cytotoxic botanical formulations used in the traditional medicine of ancient Persia as abortifacients
3
PubMed Central. Toxicities of Herbal Abortifacients – Section: 3.1. Pennyroyal (Mentha pulegium)
4
PubMed. Mitigation of pennyroyal oil hepatotoxicity in the mouse
5
Phytochemistry Reviews. Thujone, a widely debated volatile compound: What do we know about it?
6
PubMed. Toxicity of some essential plant oils. Clinical and experimental study
7
PubMed. Toxic essential oils. Part V: Behaviour modulating and toxic properties of thujones and thujone-containing essential oils
8
PubMed Central. Toxicities of Herbal Abortifacients – Section: 3.3. Rue (Ruta graveolens)
9
Wiley Online Library. Toxic Effects as a Result of Herbal Medicine Intake – Section: Herb-drug interactions
11
PubMed Central. Potential benefits versus hazards of herbal therapy during pregnancy; a systematic review of available literature
12
PubMed Central. Maternal Reproductive Toxicity of Some Essential Oils and Their Constituents
13
PubMed Central. Septic shock, acute renal and liver failure following unsafe abortion using bitter leaves and wandering jew in northern Uganda: A case series
14
PubMed Central. The Usage of Ergot (Claviceps purpurea (fr.) Tul.) in Obstetrics and Gynecology: A Historical Perspective
15
ResearchGate / Rangelands. The Effect of Poisonous Range Plants on Abortions in Livestock
16
Research Journal of Pharmacognosy and Phytochemistry. The Journey of Cyrenaic Medicinal Plant Silphium: A Review
17
Frontiers in Conservation Science. Reassessing the Role of Anthropogenic Climate Change in the Extinction of Silphium