St. John’s Wort (Hypericum perforatum L.)
St John’s Wort is a perennial plant native to Europe and much of Asia. It can grow to a height of up to 90 cm. The smooth stem, branching in the upper part, has opposite leaves which bear numerous translucent oil glands. It has yellow five-petaled flowers marked with dark dots containing red oil.
The name St. John’s Wort is believed to come from the fact that the plant’s yellow petals ‘bleed’ a red oil when crushed, and that it flowers around the 24th of June, the date on which St. John the Baptist was beheaded. The Knights of St. John of Jerusalem used it to treat wounds during the Crusades.
This herb is primarily used in the treatment of mild to moderate depression as well as anxiety and neuralgic pain. It has what is known as a thymoleptic action, which results in an improved sense of well-being, and it has a long tradition as a healing remedy in conditions such as melancholia, depression, exhaustion and during convalescence. Herbalists also use it to treat conditions where there is a degree of over-tension, such as insomnia, cramps and colic. In many conditions nervous tension and depression occur together, particularly during the menopause, and St. John’s Wort is the herb of choice here.
Both the restorative and relaxing actions of the herb are relatively long-term ones, so treatment should be continued for some time. Clinical trials have reported improved sleep quality improvements in cognitive function as well as significant improvement in mood and levels of interest and activity. In a preliminary study of St. John’s Wort combined with light therapy in patients with seasonal affective disorder (SAD), the antidepressant effect of Hypericum was shown to be enhanced by light therapy.
St. John’s Wort has a reputation as an analgesic and is used either internally or externally to treat neuralgic pain. The macerated oil can be applied externally for neuralgia and will ease the pain of sciatica. It can also soothe burns by lowering the temperature of the skin. To make a macerated oil of St. John’s Wort to apply topically for the relief of neuralgic pain (e.g. shingles and sciatica), pour half a litre of sunflower or sweet almond oil onto 120g of flowers in a glass jar, then place in direct sunlight for about six weeks or longer until the liquid has turned bright red. Strain through muslin and decant off from any watery layer.
Some anti-viral activity has been reported for the constituent hypericin.
Large doses of St. John’s Wort been reported to cause a rash and/or itching skin after exposure to UV light. This is thought to be due to the presence of hypericin. Therefore, excessive exposure to bright sunlight should be avoided whilst taking the herb.
The St. John’s Wort/drug interactions under investigation include HIV protease inhibitors (indinavir, nelfinavir, ritonavir, saquinavir), HIV non-nucleotide reverse transcriptase inhibitors (efavirenz, nevirapine), Cyclosporin, Anticonvulsants (carbamazepine, phenobarbitone, phenytoin), Digoxin, Theophylline, Oral Contraceptives, Warfarin, SSRIs (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline), Triptans (sumatriptan, naratriptan, rizatriptan, zolmitriptan).
Warning: The Medicines Control Agency (MCA) has advised that St. John’s Wort should not be taken in conjunction with certain medicines. Their concern is that it may reduce the blood levels of certain medications thereby reducing their effectiveness.
If you are considering taking St. John’s Wort in conjunction with any prescribed medication or over-the-counter remedy please contact your GP, pharmacist or herbalist for advice.