Consent has been the cornerstone of the personal data privacy regime. This notion is premised on the liberal tenets of individual autonomy, freedom of choice, and rationality. The above concern is particularly pertinent to citizen science in health and medical research, in which the nature of research is often data intensive with serious implications for individual privacy and other interests. Although there is no standard definition for citizen science, it includes generally the gathering and volunteering of data by non-professionals, the participation of non-experts in analysis and scientific experimentation, and public input into research and projects. Consent from citizen scientists determines the responsibility and accountability of data users. Yet with the advancement of data mining and big data technologies, risks and harm of subsequent data use may not be known at the time of data collection. Progress of research often extends beyond the existing data. In other words, consent becomes problematic in citizen science in the big data era. The notion that one can fully specify the terms of participation through notice and consent has become a fallacy. Is consent still valid? Should it still be one of the critical criteria in citizen science health and medical research which is collaborative and contributory by nature? With a focus on the issue of consent and privacy protection, this study analyzes not only the traditional informed consent model but also the alternative models. Facing the challenges that big data and citizen science pose to personal data protection and privacy, this article explores the legal, social, and ethical concerns behind the concept of consent. It argues that we need to move beyond the consent paradigm and take into account the much broader context of harm and risk assessment, focusing on the values behind consent – autonomy, fairness and propriety in the name of research.