What meds does grapefruit interact with?

Dextrometorphan should not be taken with Grapefruit as you will probably get hallucinations.

Edit: If you are taking normal doses of dextrometorphan and you do not have a rare sensitivity to it (because of an enzyme in your liver, or lack thereof), then grapefruit will have no effect whatsoever. As a matter of fact the relation between eating grapefruit and the effectiveness of dextrometorphan has not been successfully demonstrated. The problem with grapefruit-drug interactions is that sulfur-compounds in grapefruit juice may affect the way many meds are metabolized in the liver. This involves many antihypertensive and cholesterol-lowering agents and should probably be avoided.