St. John’s wort (Hypericum perforatum): Benefits, Uses, Safety and Dosing

St. John’s wort, also known as goatweed, Tipton’s weed, or Klamath weed, is an herb belonging to the family Hypericaceae. It is native to North Africa, Europe, and West Asia. It is currently cultivated in North America, Canada, Australia, New Zealand, and China. It was used in some ancient communities to drive away evil spirits.

St. John’s Wort is used in:

• Depressive disorders
• Alleviating menopausal symptoms
• Topically in wound healing
• Dealing with psychosomatic symptoms

Jump to section

• Medical uses and ethnopharmacology
• Safety and dosing profile
• Description and Composition
• Cultivation, harvesting and storage

Medical uses and ethnopharmacological profile of St. John’s wort

Traditional Uses

The poultice was used in wound healing (injuries, burns, scalds, neuralgia, and sciatica) to soothe skin and prevent scarring. It acted as a digestive aid in the relief of conditions like gastritis, as a diuretic for kidney stones, and for bladder irritations. In the airways it was used to clear congested airways and alleviate chronic coughs. In menstruation, it was used to alleviate symptoms of dysmenorrhea. In small doses it was used to manage enuresis, anxiety, and melancholy.

Clinical Uses and Research

Major depressive disorder: hydroalcoholic extracts of flowering plant tops administered to people with depression at a dose of 300 mg thrice daily for 6 weeks elicited a 50% reduction in Hamilton depression cases. The compounds hypericin and hyperforin showed nonselective inhibition of dopamine and SNRI by increasing intracellular sodium concentrations. ( szegedi 2005)

In another study with moderate depression, ethanolic extract at a dose of 250 mg twice daily acted by inhibiting monoamine oxidase inhibitors with comparable, though milder, action to imipramine but with fewer side effects. (EMA journal 2018)

Plaque-type psoriasis: In participants with bilateral psoriasis, 5% ointment from leaves/flowers applied twice daily for 4 weeks was able to decrease plaque thickness, erythema, and scaling. This was due to inhibition of inflammatory cytokines and reduction of T-cell infiltration of skin lesions.

Psychosomatic disorders: A standardized extract at a dose of 300 mg twice daily for 6 weeks decreased the frequency of unexplained pain and fatigue in a small, limited study. This was through the modulation of GABA and L-glutamate intake and stabilizing CNS responses to physical distress.

Menopausal symptoms: In women between 45 and 65 years, a standardized extract at 90 mg daily for 12 weeks improved or halted psychological and physiological symptoms like hot flushes. The flavonoids/mild phytoestrogens acted by stabilizing mood-related neurotransmitters affected by estrogen decline.

ADHD: In a small study with participants aged 14-16 years, a standardized extract at a dose of 300-900 mg daily improved hyperactivity and attention scores comparable to atomoxetine. The compound hyperforin increased synaptic levels of dopamine and norepinephrine in the prefrontal cortex.

In Vivo uses and Research

Wound healing: Topical application of flowery shoot ointments or macerates on rats was able to decrease wound closure time and increase tensile tissue growth. The compound flavonoids and hyperforin stimulate fibroblast proliferation and enhance the deposition of collagen in the dermis.

Neuroprotection: Standardized lowering of tops at 100 mg/kg body weight orally in a rat model normalized catalepsy and prevented dopaminergic neuronic death in the substantia nigra. The compound quercetin and hyperforin reduced oxidative stress and reduced cell apoptosis.

Neuropathic pain: Dried extract at a dose of 30-60 mg in a mouse model elicited marked relief from both mechanical and thermal hyperalgesia without any sedation effects. Hypericin acted by downregulating protein kinase C isoforms in the spinal cord. (Nicoletta 2010)

In Vitro Uses and Research

Anticancer: The ethanol extract of flowering parts showed the inhibitory action of AMPK/mTOR signaling while also activating the apoptotic mitochondrial pathway. This led to an increase in pro-apoptotic proteins while reducing MCT-T cell proliferation. (You 2020)

Anti-inflammatory: Standardized hyperforin extract showed direct inhibition of Mpegs-1 without affecting COX-1, thus blocking the inflammatory activity of prostaglandin 2 formation.

Antiviral: A purified fraction from flowers rich in hypericin showed potent inactivation of the HIV and influenza A viruses. This was through the action of inhibiting reverse transcriptase enzymes and disruption of viral envelopes.

Safety and Dosing Profile of St. Johns Wort

Forms and Dosing

Standardized capsules and tablets– 250-1200 a day

Liquid tinctures (1:5)– 2-4 mls thrice daily

Herbal infusions– teas taken up to 3 times daily

Topical oil applications– applied thrice daily

Creams and salves– applied up to thrice daily

Powders– 1-2 teaspoons

• Mild to moderate depression- 300 mg thrice daily or 600 mg twice a day
• Anxiety associated with depression- 900-1200 mg a day
• Pre-menstrual symptoms- 300 mg thrice a day

Interactions

St. John’s Wort decreases the effectiveness of the following drugs:

• Oral contraceptives
• Anticoagulants
• Antiretrovirals (protease inhibitors like indinavir and non-nucleoside reverse transcriptase inhibitors like nevirapine)
• Heart medications like digoxin
• Anticonvulsants (phenobarbitone, phenytoin, carbamazepine)
• Chemotherapy like docetaxel
• Statins like atorvastatin

The herb potentiates the effects of the following drugs and may lead to dangerous blood levels:

• Antidepressants (SSRI, SNRIs, MAOIs)
• Triptans
• Dextromethorphan
• Photosensitizing drugs like amiodarone

Side effects

• Nausea and stomach upset
• Diarrhea
• Allergies like rash, hives and photosensitivity
• Dizziness
• Sedation and fatigue
• Restlessness
• Potential decrease in libido
• Paresthesia

Contraindications

• Bipolar disorder, schizophrenia, and major depressive disorder.
• Pregnancy and breastfeeding
• Children under 12 years