Forgotten Disease traces the history of the Chinese disease foot qi (jiao qi) from its earliest occurrence in written records around the fourth century to the present day. Contemporary biomedical scientists understand foot qi to be the vitamin deficiency disease beriberi. However, Smith illustrates that historical records of foot qi denote a broad range of different symptoms, ranging from painful swelling of the feet, to a vitamin deficiency disease, to an itchy rash. Rather than assuming that foot qi has always ‘really’ been a single, unchanging disease (beriberi), Smith treats each case of foot qi she encounters as both epidemiological reality and product of the social context in which it existed. She interrogates an impressive variety of sources which span a period of a thousand years, approaching each instance of foot qi ‘not as an actor but as what is it: an experience whose meaning and parameters people define – and contest’ (p. 13).

While the idea of disease as social construct has been an established feature of histories of Western medicine since the 1990s, Chinese medicine is yet to receive the same treatment. Building on the work of authors such as Nathan Sivin and Bridie Andrews, Smith seeks to overthrow the prevailing view of Chinese medicine, which she describes as ‘particularly vulnerable to essentialization, to being presented as ancient, unified, and unchanging’ (p. 13).

Forgotten Disease begins with the earliest written record of foot qi: Ge Hong's Emergency Formulas to Keep up Your Sleeve (Zhou hou bei ji fang) written in the fourth century. According to Hong, foot qi was a ‘regional ailment’ which originated in the south of China. He asserts that people from different regions had vastly different constitutions and therefore required distinct regional therapies. People migrating from north to south, he suggests, were most vulnerable to contracting this dangerous disease. Smith presents this understanding of foot qi as an expression of anxiety over mass migration from the north China plains to the south of China which took place in the period.

Chapter 2 centres on two seventh-century medical texts: Sources and Symptoms of All Diseases (Zhu bing yuan hou lun) by Chao Yuanfang and Essential Emergency Formulas (Bei ji qian jin yao fang) by Sun Simiao. Written by elite physicians for readers with medical expertise, both texts complicated the concept of foot qi by presenting long lists of symptoms and asserting that expert knowledge was required in order to diagnose and treat it. Smith contextualizes this approach by exploring the wider medical marketplace in which Chao and Sun were operating. Elite physicians were just one of a plethora of healers offering medical care. In this competitive environment, elite physicians used convoluted diagnostic processes and the weight of classical texts as a source of authority and legitimacy.

Ge Hong was an educated layperson ‘seeking to disseminate medical knowledge to the uninitiated’ (p. 42), in contrast to elite physicians Sun Simiao and Chao Yuanfang. Smith's juxtaposition of these perspectives leads us to consider how diagnoses reflect the social context in which they are produced, the state of the medical marketplace, and, ultimately, the agendas and anxieties of the people defining diagnoses.

Chapter 3 focuses on the Song government's introduction of a public health service through state-run pharmacies and the circulation of medical books. Smith argues that simplified popular texts and standardized remedies diluted understandings and definitions of foot qi, resulting in a loss of detail and nuance in definitions of the disease in subsequent centuries. Her argument raises interesting questions about the production and dissemination of medical knowledge and the ways in which this shapes our experience of disease.

Chapters 4 and 5 deal with the expansion of foot qi from a condition which attacked the body from without to the emergence of dietary foot qi: an internally generated disease caused by excessive eating and drinking and a sedentary lifestyle. Chapter 4 examines the proliferation of regional foot qi therapies in the thirteenth century, which Smith relates to the rigid ethnic segregation which pervaded during Mongol rule. Chapter 5 considers the far-reaching social change which took place during the Ming dynasty as a result of rising prosperity and commercialization. She explores elite physicians’ use of dietary foot qi to critique the lifestyle of the nouveau riche and articulate their discomfort with a disintegrating social order.

For the final two chapters, Smith broadens her argument to consider changing foot qi definitions across East Asia from the nineteenth century to the present day. Arguably the most ambitious section of the book, the penultimate chapter uses beriberi as a vehicle for the destabilization of global narratives which position the East as inherently sick and Western biomedicine as triumphant saviour. Focusing on beriberi in Japan at the turn of the twentieth century, Smith demonstrates how Western scientific medicine, imperialism and industrialization usually ‘degraded health before improving it’ (p. 138) by disrupting local economies, medical knowledge and modes of food production.

The final chapter traces use of the terms ‘foot qi’, ‘beriberi’ and ‘Hong Kong foot’ in Japan, Korea, Taiwan and the People's Republic of China. Although her consideration of Korea and Taiwan arguably lack depth, Smith successfully highlights that ‘today's diagnoses are as influenced by today's prejudices and preconceptions as previous diagnoses had been by those of the past’ (p. 9).

As this brief introduction suggests, Forgotten Disease is not your typical disease biography; it is a rallying call for historians to stop retrospectively imposing contemporary biomedical diagnoses onto historical illnesses. Smith's sophisticated analysis offers a significant contribution to the field of East Asian studies; however, it also has much to offer a broader audience: for the general reader, Forgotten Disease is an engaging introduction to changes in the practice and experience of medicine in China over time. For historians, it is an important reminder of the textured understanding of the past we can uncover when we reject presentist interpretations of historical sources. Vitally, for historians of global and imperial histories, Smith blurs the distinctions between Asian and Western medicine and refutes tired narratives about East–West power relations with a fresh and intelligent perspective.