Even though families and friends are affected by problem gambling (PG), there is a lack of research investigating how PG affects them. In this review, the authors examined studies published up until July 2018 to explore how PG affects concerned significant others (CSOs). They also explored how CSOs attempt to minimize the harm they experience from PG. Partners are especially affected, and suffer from both physical and mental health problems. Children are also particularly affected. This review highlights a need for problem gambling service providers to reach out to CSOs.