We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Owain
saying something like:


"Tacrolimus severe overdosage after intake of masked grapefruit in
orange marmalade"
http://www.springerlink.com/content/vj2v7j3wux06201p/

Nasty. I couldn't get the article, but it mentions liver transplant
patients, to whom I asssume grapefruit is a hazard.
Same thing goes for statins, and if grapefruit is present in some
marmalades it's something to be wary of.