Quaternary ammonium compounds: outdated or relevant antiviral agents? A narrative review of QAC efficacy against enveloped and non-enveloped viruses.

Quaternary ammonium compounds (QACs) are widely used disinfectants, favored for their broad antimicrobial action and safety profile. However, viral disinfection is complex and affected by multiple variables, including the virus's envelope status, exposure time, temperature, and organic matter presence. This has created considerable ambiguity in the literature.We searched PubMed and Scopus using terms including "quaternary ammonium compounds" and "virucidal," with a focus on only registered QACs (biocides), identifying 64 studies from 419 results. These studies examined viruses from 22 families (13 enveloped, 9 non-enveloped) across different experimental conditions.QACs are highly effective against enveloped viruses, even under suboptimal conditions, and remain relevant for pandemic response. However, proper cleaning protocols are essential to ensure complete virucidal activity. Against non-enveloped viruses, QAC effectiveness is less predictable. While Parvoviridae and Picornaviridae remain highly resistant, other families like Adenoviridae, Caliciviridae, and Sedoreoviridae show variable susceptibility depending on conditions. Adding synergistic agents such as acids or alkalis can improve QAC performance and mitigate this uncertainty.