Can you eat grapefruit while taking arimidex (anastrozole)?

Not together. Grapefruit has a complex interaction on several enzymes in the liver. These same enzymes can either inhibit or magnify the effects of certain medications. So, you can eat grapefruit or drink grapefruit juice, but not during the same time as you take your medications. There is no direct evidence for arimidex, (anastrozole) but it is metabolized thru the liver, so best not to mix the 2.
Yes. No interaction between grapefruit and arimidex (anastrozole). (source: medscape/web md).