The diagnosis of drug-induced acute pancreatitis often is difficult to establish. Although some medications have been shown to cause acute pancreatitis with a large body of evidence, including rechallenge, some medications have been attributed as a cause of acute pancreatitis merely by a single published case report in which the investigators found no other cause. In addition, some medications reported to have caused acute pancreatitis have obvious patterns of presentation, including the time from initiation to the development of disease (latency). There also appear to be patterns in the severity of disease. After reviewing the literature, we have classified drugs that have been reported to cause acute pancreatitis based on the published weight of evidence for each agent and the pattern of clinical presentation. Based on our analysis of the level of evidence, 4 classes of drugs could be identified. Class I drugs include medications in which at least 1 case report described a recurrence of acute pancreatitis with a rechallenge with the drug. Class II drugs include drugs in which there is a consistent latency in 75% or more of the reported cases. Class III drugs include drugs that had 2 or more case reports published, but neither a rechallenge nor a consistent latency period. Class IV drugs were similar to class III drugs, but only 1 case report had been published. Our analysis allows an evidence-based approach when suspecting a drug as causing acute pancreatitis.