When regulated prices cannot clear shortages, non-price mechanisms determine who bears the cost. We study this in Japan's drug market, where pharmacists choose among differently priced substitutes, exploiting a government-ordered suspension of a major generic manufacturer. Out-of-pocket spending rose by up to 21%, driven by temporary shifts to brand-name drugs and larger, persistent shifts to higher-priced generics. Pharmacists' dispensing choices vary with financial incentives, yet the government's pay-for-performance program rewards generic use rather than lowerpriced generics and cannot prevent within-generic cost increases. We evaluate targeted incentives to reduce spending, and find evidence of lower adherence and higher discontinuation of treatment.