[Ethics in participatory research-reflection on challenges and possible impairments for participants].

In medical research, it is established practice to discuss ethical issues, usually based on the criteria informed consent and voluntary participation, protection from harm, confidentiality, and anonymity. The discussion of ethical questions is also gaining importance in social science research. The same applies to participatory research, which is not yet very widespread in Germany. Because this approach is based on equality between all those involved, it results in relationships uncommon in nonparticipatory research. Therefore, ethical questions are raised in a different way. Partly based on an analysis of documents, a case study from participatory health research will be used to illustrate how the principle of harm reduction can be recognized. The case study shows this from the perspective of both the researchers and the peer-researchers.From the peer-researchers' perspective, there are different challenges in participatory teamwork, which can bring impairments and consequently result in a risk of harm. This can lead to disappointments, for example, when from the peer-researchers' perspective individual support during a research process is insufficient.Conclusions for dealing with ethical aspects in participatory research projects will be derived from the gathered experiences. The application of the criteria used in nonparticipatory research can be an opportunity to strengthen the discussion of ethical issues as part of participatory processes. It can also be a chance to combine the ethical discourse in participatory and qualitative social science research.