This study describes medication error types that occur in “code” situations and also highlights their impact on other patients (referred to as “collateral damage errors” by the authors). Using data from MEDMARX, a voluntary reporting database that tracks medication information from participating hospitals, investigators evaluated more than 2000 code-related errors. Omission errors were the most common error type, registered nurses and respiratory therapists were most frequently involved (though also the most likely to prevent errors), and anti-asthma/bronchodilator medications were the most common therapeutic class implicated. The authors provide a number of anecdotes to illustrate the relationship of the errors to the code situation, and detail the level of harm and common contributing factors reported. Finally, a series of preventive strategies are offered to reduce code-related medication errors, including redundant staffing to prevent collateral damage errors, and the use of DNR identification systems and rapid response systems to reduce code frequency.