St. John's Wort: History and Traditional Use

Few common weeds carry as much history as Hypericum perforatum, the bright-yellow flower we call St. John's Wort. For more than two thousand years it has been gathered as a wound salve, a calmer of troubled minds, and a charm against evil — and its very name records a midsummer story that is older than Christianity. There is no single inventor or founder: like most healing plants, it was picked up independently by Greek physicians, medieval villagers, monastery gardeners, and later American settlers. This page traces what the record actually supports — what the old texts say, which beliefs are folklore, and the handful of firmly dated scientific milestones, from the naming of the plant's red pigment in 1942 to the modern clinical trials that brought the herb back into the pharmacy. Where a claim is tradition we say so plainly; where it is documented history, we name it.

Table of Contents

  1. A Name Rooted in Midsummer
  2. Ancient Greece and Rome
  3. Medieval Folklore and the Flight of Demons
  4. Monastery Gardens and the Red Wound Oil
  5. Paracelsus and Melancholy
  6. Crossing to the New World — and Becoming a Weed
  7. From Folk Remedy to Named Molecules
  8. The Modern Clinical Era
  9. An Honest Reading of the Tradition
  10. References
  11. Connections
  12. Featured Videos

A Name Rooted in Midsummer

The common name St. John's Wort comes from the plant's habit of flowering at midsummer, right around 24 June — the date Western Christianity keeps as the Feast of the Nativity of St. John the Baptist. ("Wort" is simply the old English word for a useful plant.) Early Christian custom attached the midsummer-blooming herb to the saint whose feast fell at the same moment, and the name stuck, displacing older names tied to pagan midsummer rites. The flowering is genuine and observable; the saintly association is a Christian-era naming tradition layered onto a much older solstice plant.

The botanical Latin tells its own story. The genus name Hypericum is generally traced to the Greek hyperikon, read by many authorities as hyper ("over") plus eikon ("image" or "apparition") — a reference to the old habit of hanging the plant over a doorway or a religious image to drive off evil spirits. This is the most commonly repeated etymology, but it is not certain: other scholars derive the word differently (for example from hyper and ereike, "heather"), so the "over an apparition" reading is best treated as the traditional and most popular explanation rather than a settled fact. The species name perforatum is on firmer ground: it is Latin for "perforated," and it describes the leaves, which appear pin-pricked with tiny translucent dots when held up to the light. Those "perforations" are not holes at all but transparent oil glands, and the dark glands along the leaf and petal margins hold the red pigment that the plant is now famous for.

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Ancient Greece and Rome

Hypericum appears in the foundational medical writing of the classical Mediterranean. The first-century Greek physician and pharmacologist Dioscorides, whose De Materia Medica shaped Western herbalism for fifteen centuries, described the plant and recommended it for a range of complaints; the Roman naturalist Pliny the Elder recorded it in his Natural History; and modern reviews of the herb's history also name Hippocrates, Galen, and Theophrastus among the ancient authorities who wrote about Hypericum species. Taken together, these classical sources are credited with recommending it as a diuretic, a wound-healing herb, a treatment for menstrual disorders, and a remedy for intestinal worms and snakebite, with sciatica, burns, and periodic fevers also mentioned in the traditional record. These ancient works are named here as historical primary sources, not as modern clinical evidence.

Two themes from antiquity run unbroken through the whole later history of the plant. The first is its use on wounds and burns — the soothing, tissue-knitting reputation that would later produce the famous red oil. The second is its association with driving out "demons": in an age when serious mental disturbance and epilepsy were understood as possession, a plant believed to expel evil spirits was, in effect, being used for what we would now call neurological and psychiatric distress. That ancient pairing — healer of the skin and queller of inner torment — is the seed of everything the herb later became.

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Medieval Folklore and the Flight of Demons

By the Middle Ages, St. John's Wort had gathered one of the densest layers of protective folklore of any European plant, and almost all of it clusters around midsummer. One of its oldest recorded folk-names is the Latin fuga daemonum — literally "flight of the demons" — capturing its reputation as a plant that evil could not abide. Folklore held that neither the Devil nor his spirits could remain near a person who carried or wore it, and the herb was hung over doors, windows, and sacred images, tucked under pillows against nightmares, and worn as a charm against witchcraft, storms, and disease. It is important to be clear that this is folk belief, recorded as such in the cultural record; it is not a medical claim.

The midsummer rituals were vivid and widespread. People gathered the flowering tops on Midsummer's Eve, the night before St. John's Day, when the herb was thought to be at the height of its power. In London and across Europe, households decked their doorways with it at midsummer; the plant was thrown onto the great St. John's bonfires, where its resinous smoke was treated as purifying, and people are recorded leaping through that smoke for protection and good fortune. A separate, poignant strand of legend tied the herb's blood-red sap to the saint himself: because crushing the buds yields a red liquid, folk tradition held that the plant "bled" on 29 August, the day commemorating the beheading of John the Baptist. None of this is biology — the red comes from the pigment hypericin in the dark glands — but the "bleeding flower" story shows how completely the plant had been woven into the religious imagination of medieval Europe.

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Monastery Gardens and the Red Wound Oil

Through the medieval and early-modern centuries, St. John's Wort was a fixture of the cultivated "physic garden" and of everyday household medicine, valued above all as a remedy for wounds, burns, bruises, and inflamed skin. The classic preparation — still made by herbalists today — is a red infused oil: the fresh flowering tops are packed into olive oil and left to steep, traditionally in sunlight, for a few weeks, after which the oil turns a deep blood-red. Historical sources describing the plant going back to antiquity already note this transformation, recording that the dried flowering tops placed in olive oil turned the oil red after about three weeks. The colour comes from hypericin and related pigments leaching out of the glands, and the resulting oil — sometimes called oleum hyperici in the old pharmacy — was rubbed on cuts, sores, burns, and aching joints.

The great European herbals carried the plant's reputation into print. The English herbalists of the sixteenth and seventeenth centuries — John Gerard in his Herball and Nicholas Culpeper in his widely read The English Physician — described St. John's Wort, and modern histories group Gerard and Culpeper with Paracelsus as authorities who recommended it for treating wounds and easing pain. These herbals are named here as historical texts. By the eighteenth and nineteenth centuries the plant had broadened in folk and domestic use, commonly made into teas and tinctures for anxiety, low spirits, insomnia, fluid retention, and stomach complaints — a quiet continuity of the old "nervine" and wound-herb roles that would, much later, be put to the test in the laboratory.

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Paracelsus and Melancholy

The single most-cited figure in the herb's history is the Swiss-German physician and alchemist Paracelsus (Theophrastus von Hohenheim, 1493–1541), the most famous medical reformer of the Renaissance. Around 1525 he is documented as recommending St. John's Wort for depression, melancholy, and "overexcitation" — that is, for disturbances of mood and the nerves. This matters because it is one of the earliest reasonably specific written links between the plant and what we would now call psychiatric use, as distinct from the older language of "casting out demons."

Paracelsus read the plant through the doctrine of his age, the doctrine of signatures, which held that a plant's appearance hinted at its God-given purpose. In St. John's Wort he and his followers saw the tiny "perforations" in the leaves — the translucent oil glands — as a sign that the herb could let light into dark places, body and mind alike, and the blood-red oil as a signature for healing wounds and the blood. The doctrine of signatures is, of course, not how pharmacology actually works; it is a historical framework of belief. But it is striking that the condition Paracelsus singled out — melancholy — is precisely the use that, four and a half centuries later, would make St. John's Wort one of the most-studied medicinal plants in the world. Tradition raised the question long before science could test it.

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Crossing to the New World — and Becoming a Weed

St. John's Wort is native to Europe, western Asia, and North Africa, not the Americas. It crossed the Atlantic with European settlers, who valued it as a medicinal and ornamental plant: records describe it being brought to eastern North America by colonists in the late 1600s (a date of 1696 is commonly cited for an early introduction). Carried for its old reputation as a wound-healer, a remedy for the nerves, and a charm against evil, it was a deliberate piece of the herbal toolkit immigrants brought from the Old World.

It did not stay in the garden. Hypericum perforatum is a hardy, fast-spreading colonizer of disturbed ground, and over the following two centuries it escaped and naturalized across the continent, reaching the western United States by around 1900. There it became a serious agricultural problem under the name Klamath weed — so called after an early infestation near the Klamath River in northern California. The plant is mildly toxic to grazing livestock and causes photosensitization (painful sunburn-like skin reactions) in pale-skinned animals that eat it, a real biological effect of the same hypericin pigment behind the red oil. By the 1940s Klamath weed had overrun hundreds of thousands of acres of rangeland and was devaluing whole districts of California pasture.

The response became a landmark in agricultural science. Importation of European leaf-eating beetles of the genus Chrysolina began in 1944, and after quarantine testing the beetles — Chrysolina hyperici and then the more effective Chrysolina quadrigemina — were released in California in 1945–1946 to control the weed. This is widely described as the first major attempt at classical biological weed control using an introduced insect in North America. It worked spectacularly: within little more than a decade the weed had been beaten back across the great majority of the infested range, and the project became a textbook success story, even commemorated with a plaque in Eureka, California. It is one of history's quieter ironies that the same plant revered in Europe as a healer and protector arrived in America as a celebrated medicine and ended up the target of one of the country's most famous weed-eradication campaigns.

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From Folk Remedy to Named Molecules

For most of its history, St. John's Wort was simply "the herb" — a whole plant with a reputation. The twentieth century turned that reputation into chemistry by isolating and naming the specific compounds responsible for the plant's most distinctive features. These are genuine, datable scientific milestones, and they are worth naming precisely.

The first was hypericin, the red pigment. Pure hypericin was isolated and characterized by the German chemist Heinrich Brockmann and co-workers, who published their study of "the photodynamic dye of St. John's Wort" in 1942. Brockmann's group proposed an initial structure for the molecule and, years later in the 1950s, achieved its total laboratory synthesis — confirming the chemical identity of the substance behind the plant's red colour, its skin-photosensitizing property, and the "bleeding" of medieval legend.

The second landmark compound was hyperforin. It was first isolated in 1971 by a Soviet research team — A. I. Gurevich and colleagues — who reported it specifically as an antibiotic constituent of Hypericum perforatum active against gram-positive bacteria; its full chemical structure was worked out by Bystrov and co-workers in the mid-1970s. For decades hyperforin was regarded mainly as the plant's antibacterial agent. Only later did researchers come to consider this unstable, oily compound a major contributor to the herb's effects on mood, a shift in understanding that helped drive the modern wave of antidepressant research. The deeper pharmacology of hypericin, hyperforin, and the plant's flavonoids is taken up in the companion Benefits articles; here the point is simply that, by the late twentieth century, the old folk herb finally had a set of named molecules to its name.

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The Modern Clinical Era

St. John's Wort's return to mainstream medicine happened largely in Germany. In 1984, the German Commission E — the expert body that evaluated herbal medicines for the German health authorities — issued a monograph approving Hypericum perforatum for depressive moods, anxiety, and nervous unrest. That official recognition, together with the development of standardized extracts, turned the herb into a genuine pharmaceutical product, and for years St. John's Wort was among the most commonly prescribed treatments for low mood in Germany, frequently outselling conventional antidepressants there.

From the 1990s onward the plant became one of the most intensively studied medicinal herbs in the world. Dozens of randomized, placebo-controlled trials and several large systematic reviews examined it for mild-to-moderate depression. The most influential synthesis, the Cochrane review by Klaus Linde and colleagues (2008), pooled 29 trials in more than 5,000 patients and concluded that standardized St. John's Wort extracts were more effective than placebo and broadly comparable to standard antidepressants for major depression of mild to moderate severity, with fewer side effects — while cautioning that results varied and that findings from German-speaking countries tended to be more favourable than others. Modern science also confirmed the old warnings in a new vocabulary: the very compounds that make the herb active also make it interact powerfully with many prescription drugs (through induction of the liver's CYP3A4 enzyme and the P-glycoprotein transporter), so that what was once an innocent garden charm is now understood to require real caution alongside medication. Those interactions and the clinical evidence are detailed on the Benefits pages.

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An Honest Reading of the Tradition

The history of St. John's Wort is unusually satisfying because the threads actually connect. The ancient and medieval world used it for two things above all: healing wounds and easing afflictions of the mind. Strip away the language of demons and divine signatures, and those two uses are exactly where modern research has concentrated — the red wound oil and the standardized antidepressant extract. It is a real example of a folk tradition pointing, however crudely, at something later borne out in the laboratory.

But honesty cuts both ways, and it matters here because real people read pages like this one. The midsummer charm against evil is folklore, valuable as cultural history, not as medicine. The herb's benefit for depression is genuine but specific — the evidence is strongest for mild-to-moderate symptoms, not severe depression — and St. John's Wort is emphatically not a harmless herb to add casually on top of other drugs: it can dangerously weaken birth control pills, blood thinners, transplant and HIV medicines, and many others, and combining it with prescription antidepressants can be hazardous. Anyone who is taking medication, is pregnant or breastfeeding, or is struggling with serious or worsening depression should talk to a doctor or pharmacist before using it. Understood that way — an old, genuinely useful plant that demands modern respect — St. John's Wort is one of the best illustrations there is of how folk medicine and science can meet.

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References

The list below combines key peer-reviewed and reference sources on the history, botany, and chemistry of St. John's Wort (Hypericum perforatum) with curated PubMed topic-search links into the historical and ethnobotanical literature. Historical primary texts — Dioscorides' De Materia Medica, Pliny's Natural History, and the herbals of Gerard and Culpeper — are named in the article as historical sources rather than as modern citations. Each external link opens in a new tab.

  1. Klemow KM, Bartlow A, Crawford J, Kocher N, Shah J, Ritsick M. Medical Attributes of St. John's Wort (Hypericum perforatum). In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd ed. Boca Raton (FL): CRC Press/Taylor & Francis; 2011. Chapter 11. — NCBI Bookshelf: NBK92750
  2. Crockett SL, Robson NKB. Taxonomy and Chemotaxonomy of the Genus Hypericum. Medicinal and Aromatic Plant Science and Biotechnology. 2011;5(Special Issue 1):1-13. — PMID: 22662019
  3. Brockmann H, Pohl F, Maier K, Haschad MN. Über das Hypericin, den photodynamischen Farbstoff des Johanniskrautes (Hypericum perforatum). Justus Liebigs Annalen der Chemie. 1942;553:1-52. — doi:10.1002/jlac.19425530102
  4. Gurevich AI, Dobrynin VN, Kolosov MN, Popravko SA, Riabova ID. Antibiotic hyperforin from Hypericum perforatum L. Antibiotiki. 1971;16(6):510-513. (Russian.) — PMID: 5000144
  5. Linde K, Berner MM, Kriston L. St John's wort for major depression. Cochrane Database of Systematic Reviews. 2008;(4):CD000448. — doi:10.1002/14651858.CD000448.pub3
  6. Hypericum perforatum ethnobotany, folklore, and history of medicinal use — PubMed: Hypericum perforatum history and traditional use
  7. St. John's Wort — hypericin, hyperforin, and the history of its chemistry — PubMed: hypericin and hyperforin chemistry

External Authoritative Resources

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Connections

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