Natural Products

St-John's Wort

Hypericum perforatum

Efficacy

• Indications with proven efficacy:
  Depression (mild or moderate)
• Indications with possible, but poorly documented efficacy - the use of this product cannot be recommended:
  Contusions, wounds and burns (topical use)
  Nervous states, anxiety
• Also used for these other indications, but with no proof of efficacy:
  Hemorrhoids
  HIV infection and hepatitis C
  Inflammation
  Menopause
  Obsessive-compulsive disorder
  Premenstrual syndrome
  Vitiligo

Security

• Risk of Drug Interactions: Moderate
• Adverse Effects: Not Frequent

What is it?

The medicinal virtues of St John's wort have been appreciated for centuries and many uses have been proposed over time. St John's wort is indigenous to North America, Europe and Australia. It has very characteristic and pretty yellow star-shaped flowers. The applicable parts of St John's wort are the leaves and flowers. Although hypericin was thought to be the component responsible for St John's wort antidepressant activities, it is now understood that hyperforin and other related compounds are the primary active constituents. St John's wort is available in capsules, tablets or liquid extracts. Products are standardized to 0.3% hypericin or 1 to 3% hyperforin.

The antidepressant activity of St John's wort may be the result of a decrease in the synaptosomal reuptake of serotonin, norepinephrine and dopamine. In addition, an enzyme called monoamine oxydase (MAO) is inhibited, but this effect is weak. Other mechanisms involving other cerebral substances may also be in cause.

St John's wort also appears to have topical anti-inflammatory effects due to its high flavonoid and tannin content.

Warning

In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) or homeopathic medicine number (DIN-HM) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.

Medicinal plants content varies naturally from plant to plant – just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.

For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at http://www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.

Does it work?

St John's wort is mostly used as an antidepressant, to control depressive moods, anxiety and nervousness:

• Mild or moderate depression:
  St John's wort has been found effective in the treatment of mild or moderate depression. The recommended initial dose is 300 mg of standardized extract three times a day, with meals. The antidepressant effect takes a few weeks to develop. The recommended maintenance dose is 300 to 600 mg per day.
• Anxiety and nervous states:
  It is believed that St John's wort is effective in the treatment of anxiety and nervousness. However this action has not been clearly established.
• Contusion, wounds and burns (topical use):
  Oily preparations are used for topical application 1 to 3 times daily. They effectively promote healing and dry up secretions. They contain substances which may be active against some bacteria.

There is insufficient reliable information to conclude that St John's wort is effective in any other indication. The effect of hypericin on HIV, the virus responsible for AIDS, is under investigation. It has already been established that the oral form is not effective against HIV. An injectable synthetic form is currently being investigated.

Is it safe?

• For most people, St. John's wort is not seriously toxic. Some people may, however, experience fatigue, gastro-intestinal upset, insomnia, restlessness, anxiety, irritability, dry mouth, dizziness, headache, and a delayed allergy or reaction to the sun.
• Its effect as a monoamine oxidase (MAO) inhibitor could caused serious undesirable reactions in the case of certain individuals after eating food rich in tyramine (example: certain aged cheeses and red wines). But this effect is weak and the real risk has not been determined.
• Patients with bipolar disorder, schizophrenia, major depression or Alzheimer's disease should avoid St. John's wort.
• This product may trigger uterine contractions and should be avoided during pregnancy. Since there is no data about the use of this product during breast feeding, it should be avoided.
• St. John's wort may reduce efficacy of cyclosporine (Neoral), digoxin (Lanoxin), tacrolimus (Prograf), theophylline, nifedipine (Adalat), some drugs against HIV, some drugs againt cancer, oral contraceptives or anticoagulants (Coumadin, Sintrom). St. John's wort can increase the adverse reactions of sibutramine (Meridia) and some antidepressants causing nausea, fever, shaking, agitation, dizziness, palpitations, and confusion. It could also increase the toxicity of volatile anesthetics used in surgery. The sedative effect of narcotics may be accentuated by St. John's wort. On the other hand, the sedative effect of barbiturates may be reduced. If you are already taking medication, check with your pharmacist to see if it is compatible with St. John's wort before using this product.

Clinical Notes

• St John's wort is a very popular natural remedy and is probably one of the most studied medicinal plant. To avoid adverse withdrawal effects, St John's wort dosages should be decreased gradually in 1 or 2 weeks.

References

1. Blumethal M et al. The Complete German Commission E monographs, 1998
2. Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2007
3. Lininger S. et Al. The Natural Pharmacy, Prima Health, 1998
4. Barnes J. et Al. Herbal Medicines, 2nd edition, Pharmaceutical Press, 2002
5. Pierce Andrea, Practical Guide to Natural Medicines, 1999
6. Passeportsanté.net. Créatine. http://www.passeportsante.net
7. Rotblatt M. et Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002
8. Herbal Companion to AHFS DI, American Society of Health-System Pharmacists, 2001
9. Scott GN. St. John's Wort and Oral Contraceptives, Pharmacist's letter, No. 190706 July 2003
10. Taylor J. CE: Phytomedicinals: Uses, precautions, and drug interactions. Drug Topics 2003;1:79