Extravasation (EV) is the inappropriate or accidental administration of medicinal drugs into the tissues surrounding the delivery site, and can be a serious complication of intravenous therapy. In previous retrospective studies of EV that relied on recall, many aspects of the situation and symptoms were unclear. In addition, the parameters and symptoms of EV that were assessed lacked uniformity, making it difficult to track the course of care. In the present study, therefore, we investigated the use of a newly devised sheet for assessment of EV to obtain a grasp of EV in actual clinical practice. We also investigated the most appropriate items and criteria for evaluating the symptoms of EV. Fifty-one patients who had suffered injury due to EV of 15 kinds of drugs were included. EV had occurred between 9:00 and 11:00 in the morning, and was often discovered by a nurse. The most frequent site of EV was the bilateral medial forearms. The acute symptoms of EV included swelling (87.5%), erythema (63.0%), tenderness (53.2%), pain (46.9%), and induration (33.3%). Our investigation showed that such symptoms were relieved or exacerbated according to the type of care given. We think that detailed observation and recording of EV using our unified assessment sheet would be valuable for clarifying the effects of care for drug EV.