Given the current bacterial resistance crisis, antimicrobial stewardship programmes are of the utmost importance. We present a narrative review of the impact of infectious disease specialists (IDSs) on the quality and quantity of antibiotic use in acute-care hospitals, and discuss the main factors that could limit the efficacy of IDS recommendations. A total of 31 studies were included in this review, with a wide range of infections, hospital settings, and types of antibiotic prescription. Seven of 31 studies were randomized controlled trials, before/after controlled studies, or before/after uncontrolled studies with interrupted time-series analysis. In almost all studies, IDS intervention was associated with a significant improvement in the appropriateness of antibiotic prescribing as compared with prescriptions without any IDS input, and with decreased antibiotic consumption. Variability in the antibiotic prescribing practices of IDSs, informal (curbside) consultations and the involvement of junior IDSs are among the factors that could have an impact on the efficacy of IDS recommendations and on compliance rates, and deserve further investigation. We also discuss possible drawbacks of IDSs in acute-care hospitals that are rarely reported in the published literature. Overall, IDSs are valuable to antimicrobial stewardship programmes in hospitals, but their impact depends on many human and organizational factors.