Grapefruit is not to be taken with some meds. why? and does this ban extend to other citruses?

Grapefruit and meds: Grapefruit and its juices contain a compound that interfers with one of the many metabolic pathways in the body. Unfortunately that pathway is a major way of metabolism for certain medications. Thus you can have accumulation of drug in your system causing toxicity. Fortunately it is only with grapefruit and not other citrus See http://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_interactions

Grapefruit and drugs: Grapefruit shouldn't be taken with many medication as cholesterol lowering drugs( statin), ca channel blockers, psychiatric drugs and many other drugs. grapefruit may increase or decrease the bioavailability of the drug through hepatic or intestinal enzyme reaction. Shaddock or Pomelo is another citrus (look like big grapefruit) may cause the same problem.