Pharmaco-toxicological aspects of thymol in veterinary medicine. A systematic review

Abstract

Introduction: Thymol, a phenolic compound present in essential oils, has shown promising pharmacological properties and potential veterinary applications. This systematic review aims to evaluate the pharmacological and toxicological eects of thymol on animals. Materials and methods: A comprehensive search following PRISMA 2020 guidelines was conducted across databases including PubMed, Scopus, Google Scholar, Web of Science, and LILACS. Various health descriptors, medical subject headings terms, and their synonyms were used to identify studies examining thymol’s eects in animals, including its in vitro, in vivo, and in silico toxicity, as well as its possible environmental impact. Only relevant experimental studies from the last 12 years were included, provided they assessed thymol itself, one of its primary phytoadditive sources, or a blend where thymol was at least as concentrated as other components. The protocol was registered in Open Science Framework (DOI: https://doi.org/10.17605/OSF.IO/B6SF9). Results: A total of 1.472 records were identified, with 176 meeting inclusion criteria. Studies spanned from 2012 to 2024, indicating that thymol exhibits antimicrobial, antiviral, antifungal, antiparasitic, anti-inflammatory, and antioxidant properties, among others. However, thymol displays dosedependent toxicity, especially at high levels, aecting mainly the liver and kidneys. Discussion: Thymol holds substantial potential as a therapeutic agent in veterinary medicine due to its beneficial eects and relatively low toxicity. Nonetheless, further research is needed to establish safe and eective dosages across dierent animal species.