It'll be affected, yes. The question is, by how much? As far as I can tell, the influence of grapefruit on the two active ingredients would be quite modest.....perhaps a 30% increase in blood concentration of the estradiol, and about 20% for the drospirenone. The risk, if any, would come from stopping the grapefruit. Breakthrough bleeding would be a sign that hormone levels had fallen into the "risky" zone.

Lar