Medical decision making, such as choosing which drugs to prescribe, requires to consider mandatory constraints, e.g. absolute contraindications, but also preferences that may not be satisfiable, e.g. guideline recommendations or patient preferences. The major problem is that these preferences are complex, numerous and come from various sources. The considered criteria are often conflicting and the number of decisions is too large to be explicitly handled. In this paper, we propose a framework for encoding medical preferences using a new connective, called ordered disjunction symbolized by ~×. Intuitively, the preference "Diuretic~×Betablocker means: "Prescribe a Diuretic if possible, but if this is not possible, then prescribe a Betablocker". We give an inference method for reasoning about the preferences and we show how this framework can be applied to a part of a guideline for hypertension.