<p>Health care worker key informant interview guide.</p>

Human immunodeficiency virus (HIV) has become a chronic condition due to improved outcomes with antiretroviral therapy (ART), resulting in increased mental health needs among people living with HIV. Women caregivers living with HIV, additionally burdened by caregiving stress, are at higher risk of mental health problems compared to their HIV-negative counterparts and the general population. In Nigeria, efforts to improve HIV-mental healthcare access largely prioritize key populations such as youth, with these caregivers remaining an underserved group. This study aimed to identify barriers to and opportunities for improving mental healthcare access for these caregivers in Nigeria. We conducted a qualitative phenomenological study involving four focus group discussions with these caregivers and 12 key informant interviews with frontline healthcare workers providing HIV services. We interviewed 52 participants (40 women caregivers and 12 healthcare workers). We analyzed transcripts using content analysis and identified themes using Levesque and colleagues’ framework for access to healthcare. This study was conducted and reported in accordance with the Consolidated Criteria for Reporting Qualitative Research (COREQ). Eight themes across five dimensions of healthcare accessibility at health system level and five corollary abilities at population level emerged. Barriers included unavailability of integrated mental healthcare-ART services, lack of training for healthcare workers on mental healthcare, stigma, lack of awareness and limited mental health literacy among the caregivers, long clinic waiting times, transportation costs and concerns for productivity losses while accessing care. Existing support groups and economic empowerment schemes emerged as opportunities for improving access to mental healthcare for these caregivers. Barriers to mental healthcare access for the women caregivers span across dimensions of healthcare accessibility at health system and patient levels, with implications for integrating mental healthcare with routine HIV services. Effectively integrating mental healthcare into routine HIV programmes requires systematically addressing these barriers while leveraging existing opportunities.