St. John’s Wort (Hypericum perforatum)

The sunny yellow flower of St. John’s wort (SWJ) holds many special significations. The genus name, Hypericum, is from the Greek, meaning “over a picture or icon”-a reference to the custom of draping the herb over religious images to strengthen their powers in banishing demons. For many centuries, St. John’s wort was a symbol of protection against evil, but also a prized medicinal herb, with the power to heal the body and ease the troubled mind.

Among the 370 temperate and tropical species in the genus Hypericum, which includes trees, shrubs, and herbaceous plants, Hypericum perforatum is best known. An erect perennial growing up to 2 feet in height, it has smooth stems that typically display ridges, dotted with tiny black spots. The opposite inch-long leaves, oblong to linear, tightly hug the stems. They have netted veins and are without teeth or have wavy teeth. Holding the leaves up to the light reveals translucent dots; the leaves appear perforated, hence the species name perforatum. The showy yellow, 5 petaled flowers, about an inch across, bloom in flat-topped clusters from early June to mis-August. The petal edges are dotted with dark glands containing a red pigment, hypericin, an active constituent and a compound associated with photo dermatitis in farm animals. When animals ear the flowers, hypericin reacts with light and oxygen to cause skin welts and lesion, a condition generally not associated with human use of plant products.

Native Range


Historical Facts

  • St. John’s wort harbor a strange secret. Bruise the delicate petals, and they seem to bleed. The blood-red liquids is an oil released from tiny, dark-colored glands scattered along the petal margins. In ancient times, a plant that “bled” was assumed to possess great powers.
  • Ancient Greek and Roman physicians used St. John’s wort to dress battle wounds, as well as treat burns, bruises, and inflammations. Hundreds of years later, as battles raged in the Holy Land, the crusaders treated their wounds with St. John’s wort in much the same way.
  • Throughout the Middle Ages, heart conditions, jaundice, dysentery, bleeding, urinary troubles, and nervous depression were all treated with the herb. Also popular at this time, and for centuries afterward, was hypericum oil, a preparation made from the flowers and rubbed in to the skin to heal bruises and wounds.
  • By the late 17th century, St. John’s wort had been incorporated into American herbal medicine prescribed externally for wounds and sores and internally for nervous anxiety and depression.
  • After falling into disuse early in the last century, St. John’s wort has seen remarkable revival in the past few decades. It is currently the most widely used herb in modern medicine for treating mild to moderate depression. St John’s wort is also used to relieve anxiety, nervous exhaustion, seasonal affective disorder, premenstrual syndrome, and to help heal minor wounds and skin irritations.

Clinical Studies/Therapeutic Uses

  • In 2009, researchers evaluated 29 clinical trials conducted on St. John’s wort for mild to moderate depression and concluded that it is more effective than a placebo and as effective as standard prescription antidepressants with fewer adverse effects. St John’s wort has gained global recognition as an effective treatment for minor depression, with 2007 worldwide sales exceeding $100 million.
  • Antidepressant medications are also used to treat severe forms of premenstrual syndrome. A pilot trial using St. John’s wort for PMS at University of Exeter in England reported a majority of women experienced a 50 percent reduction in symptoms, including anxiety and depression.
  • St. John’s wort is highly regarded as a topical agent. When the flowering tops are infused in oil-olive oil is best- the oil turns ruby red after sitting in the sun for several weeks. It is massaged in tot he skin to relieve pain or made into an ointment for wounds, burns, and insect bites. Basic science and animal studies have confirmed that the oil eases inflammation of the skin and fights bacteria.
  • Hypericin, one of St. John’s wort active constituents, has also been shown to be highly active against the human immunodeficiency virus (HIV) and herpes simplex 1-the virus known to cause cold sores and fever blisters.

Overall Benefits

  • Minor depression
  • Muscle aches
  • Fever blisters
  • Menopause
  • Anti-viral
  • Anti-inflammatory


  • St. John’s wort appears to be safe. The main risk is the potential for integration with prescription medications.
  • Safety in pregnancy has not been established


“Rebecca L. Johnson, Steven Foster, Tirana Low Dog, David Kiefer. (2010) National Geographic Guide to Medicinal Herbs. Washington DC: National Geographic Society.”

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