While there are several ways that one can get billed an unforeseen amount for healthcare in the US, the pharmacy isn’t usually it. Claims are adjudicated over a switch before you pick up your drug. You know, the pharmacy benefit or insurance knows, and the pharmacy knows who each is paying how much by the time the prescription is sold at the point of sale.

If you don’t have a pharmacy benefit or insurance, because a pharmacy is obligated to charge nobody less than certain payors, pharmacies will set up in house discount cards to give cash-paying patients a break.

Change Healthcare, a pharmacy switch that’s a subsidiary of Optum, is one of the switches that process a great share of claims. Optum is a pharmacy benefit that has administers several plans, including some of these in house discount/cash plans, manufacturer discounts, and traditional employer-sponsored plans.

It’s an interesting, little-seen bit of US healthcare infrastructure that causes some chaos across pharmacies, patients, and prescribers, when down.