What Was Castor Oil Used for in the Old Days?

Castor oil has been used by humans for at least 4,000 years, making it one of the oldest continuously employed plant-derived medicines. Its earliest documented medical applications appear in the Papyrus Ebers, an Egyptian medical text from the sixteenth century BC, which describes it as a laxative, an anti-infective, and an anti-inflammatory treatment.¹ But purging the bowels was only one chapter in a surprisingly long story that spans childbirth, hair care, lamp fuel, industrial machinery, and even political intimidation.

Ancient Egypt and the Earliest Recorded Uses

The castor plant, Ricinus communis, is native to East Africa and the Indian subcontinent, though it spread across the ancient Mediterranean world early enough that Egyptian physicians were already writing prescriptions for its oil by roughly 1550 BC. The Papyrus Ebers, a scroll now kept at the University of Leipzig, is the most famous of these early sources. It catalogs the oil’s use as a purgative for digestive complaints, a topical treatment for wounds and infections, and a remedy for inflammation.¹ Egyptian women reportedly also rubbed the oil on their skin and hair, which reflects a pattern that reappears across many later cultures.

Beyond Egypt, the oil surfaces in Greek and Roman medical texts. Herodotus, writing in the fifth century BC, noted that Egyptians used the oil from the “kiki” plant for anointing the body and for burning in lamps. Roman authors including Pliny the Elder mentioned the plant’s purgative properties alongside warnings that it was unsuitable for eating in its raw seed form. By the time of the classical world, castor oil had already settled into the dual role it would occupy for centuries: an internal medicine and an external emollient.

The Go-To Purgative for Centuries

Of all castor oil’s old uses, its role as a laxative is far and away the best remembered. For most of recorded history, physicians across cultures treated a wide range of illnesses by emptying the bowels. The logic was straightforward by the medical standards of the day: disease was thought to result from imbalances or toxic accumulations inside the body, and a strong purge was seen as restorative. Castor oil was ideal for this purpose because it worked quickly and reliably, usually within two to six hours of a single dose.

We now understand why it works so effectively. The oil is about 90 percent ricinoleic acid, a fatty acid that is released in the small intestine when digestive enzymes break down the oil. Ricinoleic acid activates a specific receptor on smooth-muscle cells in the intestinal wall, triggering strong contractions that push contents through rapidly.² The result is a thorough purge, which is exactly what physicians from ancient Egypt through Victorian England were after. Its effectiveness was never in question; what changed over the centuries was how often doctors reached for it and what they believed it could cure.

In eighteenth- and nineteenth-century Western medicine, castor oil was a near-universal remedy. It was dosed for everything from fevers and food poisoning to worm infestations and “bilious complaints,” a catch-all term for feeling sluggish and unwell. Parents routinely gave it to children as a preventive measure, a practice that produced generations of adults who recalled the oil’s thick, unpleasant taste with something close to dread. Pharmacists tried to disguise the flavor by mixing it with peppermint, orange juice, or beer, but the oily texture was hard to mask. The cultural memory of castor oil as a revolting childhood medicine persisted well into the twentieth century.

Midwifery and Labor Induction

One of castor oil’s most significant historical applications was in childbirth. Midwives in many traditions used it to start or speed up labor, a practice that continued into the modern era. In fact, castor oil has been described as the first reported medical procedure used to induce labor, with roots stretching back to ancient Egypt.³ Its use for this purpose was not just folk tradition. It was standard midwifery practice in Europe and North America through the first half of the twentieth century, and it persisted in many hospital settings even after pharmaceutical alternatives became available.

The mechanism behind this use turns out to be closely related to its laxative effect. The same ricinoleic acid that stimulates intestinal smooth muscle also activates smooth muscle in the uterus, through the same receptor.² In a pregnant woman near term, this dual action could simultaneously empty the bowels and trigger uterine contractions. Midwives and physicians who used castor oil to bring on labor did not understand the molecular details, but they had centuries of observational evidence that it could work. The downside was obvious: the laxative effect was unavoidable, making what was already an intense experience considerably more unpleasant. That trade-off is one reason the practice eventually fell out of favor in most clinical settings as more targeted induction drugs became available.

Skin and Hair Care Across Cultures

Castor oil’s cosmetic uses are almost as old as its medicinal ones. Ancient Egyptians applied it to their skin and hair, and similar traditions developed independently in South Asia, the Caribbean, and parts of Africa. The oil’s appeal for these purposes comes from its unusual physical properties: it is extremely thick and viscous compared to other plant oils, and it clings to hair and skin in a way that lighter oils do not. That viscosity makes it an effective moisturizer and sealant, locking water into the skin and coating hair strands to reduce breakage.

In South Indian tradition, applying castor oil to the hair, often mixed with coconut oil, has been a longstanding cultural and religious custom.⁴ Caribbean and African traditions likewise valued castor oil for hair growth and scalp health; Jamaican black castor oil, made by roasting and grinding the seeds before pressing, remains popular today. In Europe and colonial America, castor oil was applied to the skin for chapping, dryness, and minor wounds. Its thick consistency also made it a popular base for ointments and poultices when mixed with other ingredients.

Whether castor oil actually makes hair grow faster is a separate question from whether people historically believed it did. The oil has no proven ability to increase hair growth rate. What it does well is coat the hair shaft, reducing friction and moisture loss. For people with dry or brittle hair, that protective layer can reduce breakage, which makes existing hair appear fuller and healthier over time. That visible effect was enough to sustain its reputation as a hair-growth remedy across multiple cultures for thousands of years.

Lamp Fuel and Industrial Lubricant

Not all of castor oil’s historical uses were medical or cosmetic. In much of the ancient world, it doubled as a fuel. Egyptians burned it in lamps, as did communities across India and other parts of Asia where the plant grew readily. It burned with a reasonably bright flame, though it produced more smoke and odor than olive oil, which was the preferred lamp fuel in wealthier Mediterranean households. For regions where olive trees did not grow but castor plants thrived, the oil filled an essential practical role in daily life.

As the industrial era arrived, castor oil found a new set of uses. Its unusual chemistry gives it properties that most other vegetable oils lack. It remains stable at high temperatures, does not freeze easily, and resists breaking down under friction. These traits made it an excellent lubricant for machinery, and by the early twentieth century, castor oil was widely used in engines, particularly in high-performance and aviation applications. Early racing cars and World War I aircraft engines ran on castor-oil-based lubricants. The oil’s tendency to coat moving parts without gumming up or thinning out at extreme temperatures gave it an advantage over petroleum-based alternatives that had not yet been refined to the same degree. Pilots and mechanics during the First World War would have been very familiar with the smell of castor oil, which permeated the open cockpits of the era’s biplanes.

Processing a Dangerous Plant

One of the more remarkable aspects of castor oil’s long history is that it comes from a plant that also produces ricin, one of the most toxic naturally occurring substances known. Ricin is a protein found in the seeds of Ricinus communis, and ingesting even a small amount of raw, unprocessed seeds can be fatal.⁵ The fact that ancient civilizations figured out how to extract a safe, useful oil from such a dangerous source is a testament to how carefully traditional processing methods were developed and passed down.

The key is that ricin is a water-soluble protein, while the oil itself is a fat. When the seeds are pressed to extract oil, the ricin stays behind in the solid seed cake rather than dissolving into the oil. Heat treatment during processing further denatures any trace amounts of the protein that might remain. Properly pressed and filtered castor oil contains no ricin and is safe for ingestion and topical use. Ancient producers would not have understood this in chemical terms, but the methods they used, typically involving boiling the seeds or pressing them with heat, effectively accomplished the same separation that modern industrial processing achieves. Cultures that used castor oil across millennia clearly understood that the oil was safe while the raw seeds were not, even if they expressed that knowledge as practical tradition rather than biochemistry.

Castor Oil as a Tool of Punishment

One of the darker chapters in castor oil’s history involves its use as a weapon of humiliation and control. In early twentieth-century Italy, fascist paramilitary squads adopted forced castor oil dosing as a signature punishment for political dissidents, journalists, and anyone who spoke against the regime. Victims were held down and made to swallow large quantities, producing hours of violent diarrhea and cramping. The practice was deliberately degrading: it combined physical suffering with the public shame of losing control of one’s bodily functions.

This use was not entirely without precedent. Forced purging as punishment had appeared in various forms throughout European history. But the systematic, widespread adoption of castor oil as a tool of political violence in fascist Italy gave the substance a sinister association that lingered for decades, particularly in Italian culture. For older Italians, the phrase “olio di ricino” carried connotations not of childhood medicine cabinets but of political terror. The practice also highlights something about castor oil’s pharmacology: the same powerful, reliable laxative effect that made it medically useful also made it effective as an instrument of cruelty.

Folk Medicine Beyond the Bowels

While the laxative and labor-induction uses are the best documented, folk medicine traditions assigned castor oil an enormous range of additional roles. In various parts of the world, it was applied externally for joint pain and arthritis, often as a warm compress soaked in the oil and wrapped against the affected area. Edgar Cayce, an early-twentieth-century American alternative health figure, popularized the “castor oil pack” as a treatment for liver problems, digestive issues, and inflammation. This tradition persists today in naturopathic and alternative medicine circles, though rigorous clinical evidence for benefits beyond skin moisturizing remains thin.

Castor oil also shows up in traditional remedies for eye irritation, earaches, and fungal infections. Some of these uses have a plausible basis: ricinoleic acid does have modest anti-inflammatory properties, and the oil’s thick coating effect can protect irritated tissue from further exposure. Others, like the idea that castor oil applied to the abdomen could “detoxify the liver,” reflect the prescientific theory that diseases arose from internal toxins that needed to be drawn out or flushed away. This humoral-medicine logic drove much of castor oil’s historical popularity. Physicians were not just treating constipation; they genuinely believed that purging the digestive tract could cure fevers, headaches, and infections by restoring the body’s internal balance.

Why Castor Oil Faded from Mainstream Medicine

Castor oil’s gradual exit from the standard medical toolkit happened in stages rather than all at once. As germ theory replaced humoral medicine in the late nineteenth and early twentieth centuries, the rationale for routine purging collapsed. Doctors stopped believing that emptying the bowels could cure infections or fevers, and the list of conditions for which castor oil was prescribed shrank accordingly. At the same time, newer, milder laxatives became available that did not produce the same violent cramping and urgency. For patients who simply needed relief from constipation, gentler options like mineral oil, milk of magnesia, and eventually fiber-based supplements offered a less miserable experience.

In obstetrics, the shift away from castor oil for labor induction followed a similar trajectory. Synthetic oxytocin, introduced in the mid-twentieth century, offered a more controlled and predictable way to stimulate contractions without the unavoidable gastrointestinal side effects. Hospital-based obstetrics increasingly favored interventions that could be precisely dosed and monitored, and castor oil, which could not be titrated or stopped once swallowed, did not fit that model. By the late twentieth century, castor oil had largely disappeared from hospital maternity wards, though it persisted in home-birth and midwifery communities where its long track record carried more weight than its lack of pharmaceutical precision.

The oil never vanished entirely, of course. It remains a recognized over-the-counter laxative, it is still widely used in cosmetics and hair care, and its industrial applications as a lubricant and raw material for plastics, coatings, and biodiesel continue to grow. But the era when a family doctor might prescribe castor oil for a dozen different complaints, and when a bottle sat in nearly every medicine cabinet, is firmly in the past. What replaced it was not a single product but a shift in how medicine thinks about treatment: away from broad-spectrum purges and toward targeted interventions with understood mechanisms and controlled dosing.