To prevent and treat feline herpesvirus 1 (FHV-1), a veterinary visit, some TLC, and supplementing cat food with the amino acid lysine is often recommended. But a new study suggests that may not be such a good idea.

Researchers at the University of California, Riverside conducted a literature review of the National Center for Biotechnology Information (NCBI) PubMed database to identify the efficacy of using lysine supplementation to prevent and treat FHV-1. They concluded that not only is lysine ineffective; it may, in fact, increase the frequency and severity of FHV-1.

The study was published Nov. 16 in BMC Veterinary Research.

Per the study, lysine has no antiviral properties but works by lowering arginine concentrations that can impact FHV-1. However, the researchers note that not only does the literature review fail to support that but also that because cats cannot synthesize lysine, lowering arginine levels isn’t desirable.

The researchers also note that some feline clinical studies showed that not only is lysine ineffective in preventing or treating FHV-1; in some cases, it increased infection frequency and disease severity. 

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