Medicines may be prescribed by different practitioners at different times. Medical conditions wax (and, thankfully, sometimes wane) and the individual’s response to a particular medicine may change over time. In response, type and quantity of medicine may be altered, sometimes frequently. Patient response to medication is somewhat idiosyncratic so that a particular medicine “works” for one person but not another. Similarly, the severity of side effects or allergic reactions varies widely across patients. Beyond the prescribing, patients vary widely in their adherence to medication regimens (described as patient “compliance”).