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St John's wort (Hypericum perforatum)

From $1

What is St John's wort?

St John’s wort is a small flowering plant which has been used as a traditional herbal remedy for depression. The plant gets its name because it flowers around the feast day of St John the Baptist. In Australia, St John’s wort extracts are widely available in health food shops and supermarkets.

How is it meant to work?

The most important active compounds in St John’s wort are believed to be hypericin and hyperforin, but other compounds may also play a role. How it works is not entirely clear. However, it might increase the supply of certain neurotransmitters (chemical messengers) in the brain that are thought to be affected in anxiety. These are serotonin, norepinephrine and dopamine.

Does it work?

Social Phobia

One study has been carried out in 40 adults with social phobia. One group took St John’s wort twice a day and one group took placebo (dummy pills).The minimum daily dose was 600mg St John’s wort and each person could increase the dose up to 1800mg if they wanted to. The study lasted for 12 weeks. St John’s wort did not have any effect on the symptoms of social phobia.

OCD

A similar study was carried out in 60 adults with OCD. One group took St John’s wort twice a day and one group took placebo (dummy pills). The minimum daily dose was 600mg St John’s wort and each person could increase the dose up to 1800mg if they wanted to. The study lasted for 12 weeks. St John’s wort did not have any effect on the symptoms of OCD.

Other Anxiety Disorders

There is no evidence on whether St John’s wort works for GAD, PTSD, panic disorder or specific phobias.

Are there any risks?

When taken alone, St John’s wort has very few side effects. However, St John’s wort interacts with many prescription medications, either affecting how these medications work or producing serious side effects. According to the Therapeutic Goods Administration, people taking any of the following medications should not start using St John’s wort:

  • HIV protease inhibitors (indinavir, nelfinavir, ritonavir, saquinavir)
  • HIV non-nucleoside reverse transcriptase inhibitors (efavirenz, nevirapine, delavirdine)
  • Cyclosporin, tacrolimus
  • Warfarin
  • Digoxin
  • Theophylline
  • Anticonvulsants (carbamazepine, phenobarbitone, phenytoin)
  • Oral contraceptives (‘the pill’)
  • SSRI antidepressants and related drugs (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, nefazodone)
  • Triptans (sumatriptan, naratriptan, rizatriptan, zolmitriptan)

Anyone who is taking any other medications and wishes to use St John’s wort is advised to check with their doctor first.

Recommendation

Initial evidence suggests that St John’s wort does not appear to be effective for OCD or social phobia. However more research is needed.

References

Kobak KA et al. St John’s wort versus placebo in obsessive-compulsive disorder: results from a double-blind study. International Clinical Psychopharmacology 2005; 20:299–304.

Kobak KA et al. St. John’s wort versus placebo in social phobia: results from a placebo-controlled pilot study. Journal of Clinical Psychopharmacology 2005; 25:51–58.

 
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