St. John's Wort - Hypericum perforatum

Common Names: St. John's Wort, St. John's herb, St. John’s grass, Herb of St. John, Saint John’s wort, Perforate St John's-wort, Common St John's-wort, Klamath weed, Tipton's weed, Rosin rose, Chase-devil, Goatweed, Hypericum perforatum, Třezalka, Bylina sv. Jana, Bloodwort, Origin: Europe

Latin Name: Hypericum perforatum

Origin: Africa, Asia, Europe, South America

Short Introduction

St. John's Wort reproduces both sexually (by seed) and asexually (vegetatively), choosing its strategy depending on environmental conditions such as moisture (seasonal changes like winter vs. summer). The plant is more resilient to extreme factors than many others but has certain limits: it grows poorly above 1,500 meters, in excessive humidity, or outside an optimal temperature range (14–24°C). Its growth and propagation strategy is influenced by environment and age; during wet summers, vegetative growth predominates before switching to sexual reproduction via pollen. St. John’s Wort seeds can survive in frozen soil for several years until favorable conditions return.

Though often cultivated commercially (from Eastern Europe to southern Africa and New Zealand), some farmers consider St. John’s Wort an invasive weed. It is highly resilient, capable of overtaking native plant habitats, and acts aggressively in pastures—posing risks such as photosensitivity, central nervous system depression, rare miscarriages, or death to livestock that consume it. Its hardiness makes it suitable for beginner gardeners. The most valued part is the upper flowering stems, ideally harvested early in the morning around St. John’s Day (June 24), according to traditional lore.

Detailed Description

St. John's Wort is nature’s most recognized herbal antidepressant, used for centuries to support sleep and address difficulties falling asleep.

Botanical Information

St. John's Wort (Hypericum perforatum) is an annual herb typically reaching a height between 25 and 60 cm, though it can grow up to 1 meter. It features a woody, upright stem with most branches concentrated near the top. The elongated rhizome supports alternating, elliptical, yellow-green leaves several centimeters long, each marked by distinctive black dots—oil glands characteristic of this species. The regular, five-petaled flowers are bright yellow, and the fruit is a capsule.

Origin and Distribution

Native to Europe, St. John's Wort has now spread across the globe. In its native habitat, it thrives almost everywhere outside Arctic regions, mostly from lowlands to submontane elevations. It prefers sunny slopes, dry meadows, roadsides, forest edges, and field margins. The species is also widespread throughout eastern Asia and as far as Asia Minor; in Africa, it is common in the north, and it has been naturalized in the Americas, where its distribution is limited mainly by altitude.

Usage / Dosage

The best-known and most widely used effect of St. John's Wort is as a moderate strength herbal antidepressant. Numerous studies confirm the stimulating effects of its compounds for mild depression and light anxiety. In folk medicine, it features in many traditional remedies for inflammation, skin eczema, bruises, and fractures. The same sources attribute antibacterial properties that can help soothe skin infections. Regarding impacts on the central nervous system, St. John’s Wort is used therapeutically for stressful situations, premenstrual syndrome, muscle pain, and other psychological difficulties associated with nervousness and stress.

Some healers have found it useful for dizziness and discuss its potential to reduce internal bleeding that may be linked to weakened vascular wall integrity. An oil macerate from St. John’s Wort flowers, often prepared in olive or sunflower oil, forms a ruby-red oil known for its calming and mild antidepressant effect. This oil is recommended for the external treatment of burns, frostbite, wounds, hemorrhoids (relieving burning and itchiness), and ulcers. Warmed, it is used in muscle massage during therapy for muscle diseases, especially in Central Europe.

In countries like Germany, St. John’s Wort and its extracts are routinely prescribed for moderate depression, with regulation requiring clinical studies supporting their efficacy and strict quality controls on the active ingredients hypericin and pseudohypericin. These two compounds are the most thoroughly researched constituents in St. John’s Wort.

A review of 29 studies by the Cochrane Collaboration confirmed that St. John's Wort is more effective than a placebo and has comparable effectiveness to standard antidepressant medications, with fewer and less severe side effects. Long-term studies are ongoing.

Researchers have investigated the compound hyperforin for its potential impact on alcoholism and antibacterial activity. Folk medicine attributes the anti-inflammatory and antibacterial properties of St. John's Wort extracts largely to this compound. There is also evidence for antiviral effects in mildly infected volunteers, and ongoing studies are assessing its potential in treating Parkinson’s disease.

St. John’s Wort is contraindicated for those with low blood pressure, diabetes, or allergies. Prolonged use may cause increased sensitivity to ultraviolet light. Identification is important, as some look-alike species or other St. John’s Wort varieties are less well tolerated and lack proven benefits; harvesting with an experienced herbalist is strongly recommended. Caution is advised for patients taking other medications, including hormonal contraception, so always consult a healthcare professional regarding potential drug interactions.

Active Compounds

St. John's Wort contains various valuable compounds, most notably flavonoids (including rutin, isoquercetin, quercetin, and kaempferol), which support vascular wall health by providing elasticity and tensile strength. The most important active molecules for antidepressant effects are hypericin, pseudohypericin, and hyperforin—all of which are associated with the herb’s photosensitizing side effects. These can be observed in the oil reservoirs of the leaves, a key trait behind the species' “perforated” name. Additional compounds include tannins, phenols, unsaturated fatty acids, phloroglucinols, and vitamins.

Traditional Dosage

Recommended dosages of St. John’s Wort vary by age, indication, and location. For example, the Mayo Clinic in the United States suggests 0.9 grams twice daily for adults experiencing mild to moderate depression or anxiety. Czech sources recommend up to three doses a day. For an herbal tea infusion, use 1 teaspoon of dried herb steeped for 15 minutes in a cup of water, up to 3 times daily.

St. John's Wort oil can be purchased or made at home, but correct identification of the true species is essential. To prepare, infuse approximately 150 g of freshly cut and chopped flowering herb in 0.5 liters of high-quality oil (preferably olive) in a covered container. Let the mixture stand uncovered in a cool, dark place for a few days, then seal and steep it in a warm, sunny spot for several weeks (ideally 6 weeks). The finished oil will have a strong ruby-red color. The longer it is infused, the better the result. 1 teaspoon of this oil can be taken up to 3 times daily.

Warning: St. John's Wort may cause photosensitization (increased sensitivity to UV light).