This study aimed to culturally adapt the English-language mental health first aid guidelines for depression to the Brazilian culture. This adaptation was accomplished by a two-round Delphi study involving 29 health professionals with experience in depression and 28 consumers and carers with lived experience of depression in Brazil. There were similarities and differences between the English-language and the Brazilian guidelines.Comparison with the English-language guidelinesOf the 174 English-language statements presented to participants, 128 statements were endorsed in the Round 1 survey, and five statements were endorsed in the Round 2 survey, showing a high level of similarity (i.e., 76% agreement) between the English-language and the Brazilian adapted mental health first aid guidelines for depression. Key differences involved excluding 41 original English-language statements and the addition of 10 new statements. Statements related to respect for the autonomy of a person with depression, such as respect for personal feelings and experiences, were excluded from the adapted guidelines. For instance, the following statements from the English-language guidelines “The first aider should be open to any opportunity that presents itself to talk about their concerns with the person” and “The first aider should know that allowing the person to talk about how they are feeling can help them feel better, not worse” received low ratings by both panels. This may be because mental health problems are stigmatized in Brazil , even among mental health professionals , and talking openly about a mental health problem may be considered demeaning to a person with depression in Brazil.Furthermore, statements related to the first aider prioritizing the person’s safety above all were seen in the Brazilian adapted guidelines. For example, statements from the English-language guidelines “The first aider should not assume that any signs or symptoms they have noticed means that the person is experiencing depression” and “The first aider should not assume that the person’s symptoms are due to depression” were not endorsed by either panel. This may be because involuntary psychiatric admissions are seen as an acceptable measure to protect individuals and society, with one in five patients in Brazil being involuntarily admitted to hospitals . Moreover, this idea of prioritizing the safety of a person with a mental health problem and involuntarily admitting them to hospitals may be a potential source of shame and stigma towards the person and their family within the Brazilian society [12,13,14].Statements related to the importance of family involvement when providing support to someone with depression were also added to the Brazilian guidelines. For instance, a statement created from participants’ comments (“The first aider should check if there is someone in the family who can accompany the person in their treatment”) was endorsed by all health professionals and all consumers and carers, showing the centrality of family within the Brazilian culture . The focus on family seen in this study is in line with previously adapted mental health first aid guidelines for depression for other countries with collectivist cultures such as Sri Lanka  and China , where family involvement was also an essential factor in their adaptation of the guidelines.Moreover, empathy-related statements were found to be culturally specific to the Brazilian guidelines. Firstly, statements from the English-language guidelines related to the importance of empathy were highly endorsed by both panels in round 1; for example, over 95% of participants in both panels believed the statement “The first aider should know that the key attitudes involved in non-judgmental listening are acceptance, genuineness and empathy” should be included. Likewise, two of the newly created and highly endorsed statements were related to empathy. This is in line with what Mascayano and colleagues highlighted as a fundamental aspect of Latin culture – the importance of showing empathy .Differences between panelsDifferences in ratings between the health professional and consumers and carers greater than ±10% were observed. For instance, panels had opposing views on the extent to which people with depression should be responsible for their recovery – all consumers and carers endorsed the statement “The first aider should know that recovery, for the most part, must be led by the person”, while only 62% of professionals endorsed this statement. Likewise, consumers and carers thought it was more important for people with depression to use self-help strategies that worked for them in the past. More than three quarters of the consumers and carers endorsed the statement “The first aider should encourage the person to use self-help strategies that have helped the person in the past”, while only half of the professionals endorsed this statement. Finally, consumers and carers thought it was more important to seek advice from people who have recovered from depression than health professionals did – 80% of the consumers and carers endorsed the statement “The first aider should learn more about depression by seeking advice from people who have experienced and recovered from depression”, while only 69% of the professionals endorsed this statement. This may reflect the relatively less well-developed consumer advocacy movement in countries such as Brazil, as well as a lower emphasis on the agency of the person with depression [33, 34].Considerations for future use of the adapted guidelinesThis study aimed to culturally adapt the English-language mental health first aid guidelines for assisting a person with depression to Brazilian culture by using opinions and views from health professionals and individuals with lived experience of depression in Brazil. As these guidelines’ adaptation showed some similarities and differences from the English-language guidelines, this provides further support for the importance of culturally adapting the guidelines.The Brazilian adapted guidelines will be a stand-alone document and may also be used to guide the development of MHFA training. It is, however, important to note that the statements from these guidelines, which were assembled into sections, should not be taken individually as they may be more effective when used as a whole. The guidelines and the MHFA training may play a role in improving mental health literacy and reducing stigma in Brazil, although further research into development, implementation and effectiveness in Brazil is required to assess this.Strengths and limitationsA strength of this study was the systematic and evidence-based method used to adapt the English-language depression guidelines for Brazil. This adaptation allowed aspects of this culture, such as family involvement and empathy, to be incorporated into the adapted guidelines. Another strength of this study was the participant diversity, including, critically, people with their own lived experience and experience as carers. This ensured that widely varying views and opinions were gathered, which is fundamental in Delphi studies .A limitation of this study was the low retention rate of participants in round 2, with the 50% retention rate not reaching a recommended 70% rate, possibly due to the time required to complete the questionnaires. However, the retention rates between both panels were similar, meaning that it is unlikely that one group of expert panelists had undue influence on the results. This drop-out rate may also impact on the generalizability of the findings.