"A high-standard systematic review conducted in 2009 concluded St John’s Wort extract was superior to placebo in patients with major depression and similarly effective to standard treatment with SSRIs. They also found fewer people taking St John’s Wort discontinued their treatment. This was due to them experiencing fewer side effects."
Joanna Harnett, Associate Lecturer Faculty of Pharmacy - Complementary Medicine, University of Sydney, explains the historical and current use of St John’s Wort, how it works, its safety and side effects. Note particularly "It is generally well tolerated, but adverse effects may occur. These include mild gastrointestinal symptoms, skin reactions, increased sensitivity to sunlight, fatigue, sedation, restlessness, dizziness, headache and dry mouth." and the important concluding reminder that "The use of St John’s Wort should be guided by a health-care professional who is knowledgeable about the quality of available products, effective dosing and safety considerations, including known drug interactions associated with its use."
The article comments are worth a read too, in particular that by David Kemp, Professor of Agricultural Systems, Charles Sturt University regarding observed side effects in sheep grazing on pastures containing St John's Wort: "I would think a more cautionary note needs to be put into articles such as this. It is evident that the author has not read the veterinary and poison plant literature (see papers by C Bourke). The big problem is the concentration of active ingredients varies through the year, and varies between ecotypes (there are three main types in Australia). Unless you do a lot of testing you have no guarantee of what dose you may get. Anyone who has seen photo-sensitisation in sheep knows you need to be cautious. Fortunately there is genetic variation in sensitivity, but graziers have to carefully watch animals if grazing where St John’s Wort is present."
Further confirmed by the author: "It is common knowledge amongst herbalists that SJW can cause photosensitivity depending on harvesting and manufacturing practices."
There are a few reasons why I posted this article:
1) There is excellent evidence that the natural product St John's Wort has a pronounced pharmacological effect
2) Despite the mistaken belief by many that natural products are a better alternative to manufactured drugs, just as with any prescribed drug, there are known side effects from St John's Wort as well as interactions with other medications
3) St John's Wort reduces the effectiveness of Ibrutinib:
4) The concentration in the level of active ingredients varies during the year - an inherent problem common with natural plant based supplements
These are the reasons it is critical that you inform your medical team of any complementary/alternative supplements you are taking and why you should very carefully proceed with taking multiple complementary/alternative supplements concurrently.
Photo: Not St John's Wort, but flowering Canola