Hmm, doing some more reading I found this (from http://www.personalhealthzone.com/stjohnswort.html)

"Avoid the following substances when using St.-John's-wort: Amino acids tryptophan and tyrosine; amphetamines; asthma inhalants; beer, coffee, wine; chocolate, fava beans, salami, smoked or pickled foods, and yogurt; cold or hay fever medicines; diet pills; narcotics; nasal decongestants. They all contain chemicals that react adversely to hypericin, causing high blood pressure and nausea."

Beer and pickles! I don't want to give those up! Oh well, I suppose I can switch to wine or whiskey.