Financial incentives for participants in health research: when are they ethical?

Publication Date: 16.03.2022
Swiss Med Wkly. 2022;152:w30166

Tania Manríquez Roaab, Nikola Biller-Andornoab

a Institute of Biomedical Ethics and History of Medicine, University of Zurich, Switzerland

b Digital Society Initiative, University of Zurich, Switzerland

Offering financial incentives to recruit participants, retain them and promote health-related behaviours is a common practice in health research. The development of health research standards has given rise to a rich and long-standing debate regarding the ethical issues associated with the use of financial incentives. Some researchers argue that financial incentives compromise the integrity of the research process and its outcomes. Since financial incentives can influence decision-making, they may jeopardise the voluntariness of research participants’ consent. In particular, they argue that the use of financial incentives may lead to undue inducement, exploitation and biased enrolment of research participants. At the same time, other researchers argue that financial incentives represent a flexible tool that can be designed in ways that do not compromise scientific integrity. They highlight that financial incentives can be fair inducements for participation, a way of acknowledging participants’ time and effort, and a means to achieve diverse sample compositions. They also point out that in some situations, these incentives can enable research that would otherwise be unfeasible.

In health research, financial incentives are monetary benefits (e.g., payments, vouchers, gifts) that are used in the recruitment process to get an adequate sample size and composition, to retain participants throughout the course of the study, or to promote health-related behaviours or outcomes. Although the general discussion on these incentives has developed substantially in recent years, different ethical implications may arise depending on the specific nature of the research that is being conducted and the purpose of using financial incentives in each study. An emerging area of health research where this discussion merits further attention is implementation research involving financial incentives to promote health-related behaviours and, more specifically, research of this kind carried out in low-income settings. 

International ethics guidelines have advanced in providing more specific recommendations over time. The Helsinki Declaration briefly established the requirement to include information regarding incentives for participants and compensations for harm in study protocols [1], and more recently the Council for International Organizations of Medical Sciences (CIOMS) provided detailed recommendations on how to define reimbursements and compensations [2]. CIOMS also highlighted the danger of undue inducement, defined what are appropriate and unacceptable compensations, suggested ways to establish adequate monetary compensations, stressed the need to compensate people who are incapable of giving an informed consent in a way that benefits them and stated that participants must receive proportional compensation when they withdraw from a study – owing to either research-related harm or unwillingness of the participant to continue [2]. Although paying study participants is generally accepted in health research, countries have different approaches to establishing when payments are allowed. In Switzerland, for instance, no person can receive a payment or non-cash advantage for taking part in a research project that has an expected direct benefit [3]. Offering financial incentives to promote health-related behaviours is not explicit in this norm, but in principle they could be allowed as long as the behavioral requirements are freely accepted by participants, limited in time, and not excessive, disproportionate or harmful.

The academic literature distinguishes three acceptable rationales for payments to research participants: reimbursement of out-of-pocket expenses, compensation for the time and burdens of participation, and incentives to participate [4]. Although reimbursements and compensations remain relatively uncontroversial, incentives have raised an academic debate. Advocates argue that the use of financial incentives in health research offers potential advantages for different types of studies and in various socioeconomic contexts. For example, financial incentives are thought to be relevant in the recruitment and retention of healthy participants for phase I clinical trials, and in studies carried out in socioeconomically disadvantaged populations – either in poorer countries or in impoverished areas of richer countries [5]. Although this raises ethical concerns, financial incentives could overcome financial barriers to participation and be effective in obtaining samples with sufficient socioeconomic, ethnic and gender diversity. Interestingly, the potential advantages for health promotion are analogous: financial incentives can be effective and benefit society at large by fostering behavioural change and removing financial barriers so that individuals can adopt new behaviours [6].

There are four main ethical concerns regarding the use of financial incentives in health research. First, financial incentives can lead to undue inducement and, therefore, compromise the voluntariness of participant’s consent. The argument is that financial incentives can undermine participants’ autonomous decision-making because people can be encouraged to make a financially motivated decision against their better judgement [5]. Second, there is the concern of exploitation. Participants can be exploited if they are not offered an adequate compensation considering their contribution in terms of time, effort, inconvenience and opportunity costs. Third, financial incentives could lead to biased enrolment. Payments can motivate people from vulnerable groups (e.g., socioeconomically disadvantaged populations) to participate in research at a higher rate than people from privileged groups. This kind of biased enrolment jeopardises the generalisability of research results, and is unfair because the benefits and burdens of research would be distributed inequitably among socioeconomic groups [5]. Fourth, the use of monetary incentives to promote health in the context of research can be a form of bribery. Even if having healthy behaviours is in the interest of the person being paid for maintaining them (e.g., following a healthy diet), financial incentives can induce people to do the right thing for the wrong reason. Health bribes may trick people into doing something they should be doing anyway, and they may undermine attitudes that are relevant for good health, such as treating our bodies with care and respect [7].

The role of financial incentives in influencing health-related behaviours and reaching health outcomes merits a closer look. Especially, we need to have a broad discussion regarding the ethical implications of the widespread use of financial incentives in implementation research in health. Implementation research aims to improve access to proven interventions and to identify processes to implement and scale-up established evidence, primarily in low-resource settings. Examples of implementation research include offering financial incentives as a means to overcome economic obstacles to access maternal healthcare, or as means to incentivise parents to vaccinate their children. International documents offer limited guidance. Neither the Helsinki declaration nor CIOMS address the use of financial incentives in implementation research in health. Recently, a World Health Organization (WHO) guideline proposed that, when used in implementation research, financial incentives may enhance autonomy and support participants in bringing about changes they wish for [8]. However, this guideline stressed that incentives may also undermine autonomy, exacerbate inequalities, create unforeseen risks, destabilise local economies or lead to exploitation [8]. Financial incentives have raised some controversies in implementation research, and an illustrative example is their role in promoting breastfeeding. On the one hand, besides the ethical concerns already mentioned regarding financial incentives in general, a claim against offering incentives in breastfeeding studies is that they allow a specific form of  bribery. The argument is that breastfeeding is an element of responsible parenting and thus no additional incentive is needed or deserved. On the other hand, some researchers suggest that carefully designed financial incentives can be ethically justified if one considers the benefits of breastfeeding, the wide socioeconomic, racial and ethnic disparities that hamper breastfeeding, and the prominent influence of formula marketing [9].

Defining when financial incentives might be suitable or not in health research studies is an important task ahead. It remains to be discussed how to weight the ethical issues at stake when offering financial incentives to influence behaviour in implementation research, the relationship between incentives and health outcomes in the context of socioeconomic disparities, and how to establish adequate incentives to influence health-related behaviours and outcomes. A public debate on financial incentives for participants in health studies will encourage the generation of better guidance for researchers, and contribute to safeguard participants’ well-being in the creation of high-quality knowledge.


Webinar “Offering Financial Incentives to Participants in Health and Breastfeeding Research”

This online event is organised by the Forum for Global Health Ethics, an initiative of the Institute of Biomedical Ethics and History of Medicine (University of Zurich), together with the Swiss Medical Weekly, The Global Health Network (University of Oxford) and LactaHub (A Resource for Evidence-Based Breastfeeding Intelligence).

April 13, 2022
9:00 to 10:30 ET / 15:00 to 16:30 CET


  • Mary Ani-Amponsah (University of Ghana, Ghana)
  • David Resnik (National Institute of Environmental Health Sciences, United States)
  • David Yanagizawa-Drott (University of Zurich, Switzerland)

You can register here:


The authors thank Supriya Subramani for sharing literature and documents with her work on the topic, and Roberto Andorno for providing insights and expertise valuable for the text.

Tania Manríquez Roa thanks the Digital Society Initiative and the Institute of Biomedical Ethics and History of Medicine, both at the University of Zurich, for funding her research.

Disclosure statement

Both authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflict of interest was disclosed.


Prof. Nikola Biller-Andorno, MD, PhD

Institute of Biomedical Ethics and History of Medicine

University of Zurich

Winterthurerstrasse 30

CH-8006 Zurich



1. World Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA. 2013 Nov;310(20):2191–4. PubMed 1538-3598

2. Council for International Organizations of Medical Sciences (CIOMS). International ethical guidelines for health-related research involving humans. Geneva: CIOMS; 2016. 122p.

3. Swiss Federal Act on Research Involving Human Beings. Art. 14 Non-remunerative participation,

4. Gelinas L, Largent EA, Cohen IG, Kornetsky S, Bierer BE, Fernandez Lynch H. A Framework for Ethical Payment to Research Participants. N Engl J Med. 2018 Feb;378(8):766–71. PubMed 1533-4406

5. Resnik DB. Bioethical Issues in Providing Financial Incentives to Research Participants. Medicoleg Bioeth. 2015 Jun;5:35–41. PubMed 2230-2468

6. Gopichandran V, Luyckx VA, Biller-Andorno N, Fairchild A, Singh J, Tran N Developing the ethics of implementation research in health. Implement Sci. 2016 Dec;11(1):161. PubMed 1748-5908

7. Sandel MJ. What Money Can't Buy: The Moral Limits of Markets. New York: Farrar, Straus and Giroux; 2012.

8. World Health Organization (WHO). Ethics in Implementation Research, Facilitator's Guide. Geneva: WHO; 2019. 172p.

9. Hoskins K, Schmidt H. Breastfeeding, personal responsibility and financial incentives. Public Health Ethics. 2021 Nov;14(3):233–41. 1754-9981

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