She shouldn't drink it at all. The duration of the grapefruit inhibition of 3A4 is roughly 3 days. Of course, the dose of grapefruit juice, and the manner in which it is prepared (home-made is safer than commercial), etc. etc. influence things, also. Because there are toxic consequences from statin overdose, the prohibition is quite reasonable. Not all statin drugs are affected to the same extent, so you can't generalize......but Lipitor is definitely affected by grapefruit.

Lar