A paper briefing two case studies in Canada showing possible adverse effects of St John's Wort

These are only two case studies and the authors note there's no
established causality.
http://www.cmaj.ca/cgi/content/full/163/3/262-c

There's another paper I have to read which is a review of literature.
Someone brought to my attention that St John's Wort may cause mania and
psychosis. "May" may mean there's a 0.01% risk or a 99.99% risk
depending on the author's level for which it's worth mentioning a risk.
On the about.com page it's noted that SJW "may" cause psychosis and
mania. Two case studies wouldn't be enough for me to mention those risks
if I were writing healthcare information. Let's see what the other
papers say.