本文以隋代（581-619）至宋代（960-1279）討論治療嶺南（宋時地理範圍涵蓋現今廣東、廣西省、海南島）瘴病的文本為主要史料，考察文本作者用哪些方法支持他們所提出的治療方法。南宋以前，提到防治嶺南瘴病的文本大多出現在醫書中。這些醫書的作者多強調所收錄之藥方為已經使用過、證明有療效的「驗方」。現存南宋討論瘴病治療與防範的作品不只見於以收錄藥方為主的醫方書，還出現在一些被歸入史部地理類的作品。這些南宋文本的作者在論說自己對治療或防範瘴病的看法時，多援引自身在嶺南的親身見聞為據。他們對親身見聞和嶺南風土特色的強調，依據文類的不同，一方面呼應了十一世紀以降，部分士人認為醫方書應記載該如何配合患者體質與地理等個人差異而用藥；另一方面，則呼應了南宋時許多筆記文體的作者強調個人親身見聞的趨勢。

This article investigates extant accounts of treating zhang (瘴 “miasma”) disorders in Song dynasty Lingnan 嶺南, a region largely encompassing presentday Guangdong province, Guangxi province and Hainan island at that time, and mainly concerns how authors enhanced the trustworthiness of these accounts. Authors of pre-Southern Song medical literature who mentioned prescription strategies for treating zhang for the most part stressed the fact that the recipes collected in their works were tested and proven effective. This was their primary means of establishing trustworthiness. By contrast, the majority of Southern Song authors writing about zhang medicine sought to render their claims more authoritative by including details drawn from their own experience of the environment and of cases they had treated in Lingnan, adopting what I call a “personally-verified approach.” There is a significant concurrence between the increasing emphasis by authors of Song formularies (fangshu 方書) and jottings (biji 筆記) on documenting particularities they had experienced and observed in specific places, and the emergence of writing based on authors’ own experiences and observations of regional features in Southern Song zhang medicine. In formularies, this trend was a response to a growing expectation for individual particularities to be taken into account, and served as a new criterion among educated readers for assessing the reliability of formularies. Jottings, a literary form whose popularity soared in the Southern Song, also highlighted knowledge acquired by authors through first-hand observation and from conversations. Accounts of zhang texts containing information about Lingnan were a popular topic of conversation at social occasions of the day, a fact which also fits our general understanding of the social implications of jottings, and an example of how oral discourse and literature were interconnected. This paper argues that the Southern Song was a crucial period that witnessed a closer interlinkage between the consolidation of written medical knowledge and the changing social implications of and criteria for accepted scholarship.