The stigma and discrimination experienced by individuals with an alcohol/substance use disorder often extends to the family members and friends who provide care, which is known as courtesy stigma. This courtesy stigma can lead to isolation, poor mental health and might impact the quality-of-care these individuals provide. The aim of this study was to examine the frequency of experienced courtesy stigma/discrimination in individuals in a family support service for a loved one's substance use, and to examine any cross-sectional associations with changes in mood, health- and social-related outcomes. Thirty-six individuals (25 female) with a mean age of 51.91 years took part in an ecological momentary assessment study in which the experience of courtesy stigma/discrimination and measures of mood, health (e.g. alcohol use, nicotine use, healthy eating, sleep, physical activity) and social connections were taken 3 times per day for fourteen days. Across 1029 competed assessments (compliance ∼68%), there were 122 (∼11%) reports of courtesy stigma/discrimination. The most common sources of stigma/discrimination were from family members (∼43% of occurrences) and friends (∼31% of occurrences). Experiencing this stigma/discrimination was associated with increases in alcohol and nicotine use, as well as reductions in healthy eating, physical activity, sleep, social connections, and mood. The experience of courtesy stigma/discrimination was common in a sample of individual's who support a loved one with alcohol or substance use disorder. These experiences are associated with changes in health and social behaviors and may lead to a poorer quality of care.