In Binding of Issac Wraith of the Lamb I picked up a Range Down Pill that I already identified. Some time during the play-through it changed to a Range Up Upgrade. I am not sure when it happened or what happened. I know that that the Lucky Foot Item and the PHD can change negative pill effects, but neither one of those items were picked up in this run.
Are there any other items that could of changed the pill type?
If you hold on to a known negative pill long enough does it change?