Favipiravir Observational Study Interim Report 3
, Fujita Health University, Apr 2021
Retrospective analysis of favipiravir use in 10,986 hospitalized patients, including analysis of changes in clinical status and side effects. Common adverse events were uric acid level increase and liver function enzyme increase. Authors note that early embryonic lethality and teratogenicity due to favipiravir have been observed in animal models, that pregnant women must be excluded, and that all patients and partners should practice effective contraception.
Potential risks of favipiravir include kidney injury1-3, liver injury2-4, and mutagenicity, carcinogenicity, teratogenicity, embryotoxicity, and the creation of dangerous variants5-11.
1.
Abdulaziz et al., Clinical Features and Prognosis of Acute Kidney Injury in Hospital-Admitted Patients with COVID-19 in Egypt: A Single-Center Experience, Mansoura Medical Journal, doi:10.58775/2735-3990.1433.
2.
Ülger et al., Experimental evaluation of favipiravir (T-705)-induced liver and kidney toxicity in rats, Food and Chemical Toxicology, doi:10.1016/j.fct.2025.115472.
3.
El-Fetouh et al., Experimental Studies on Some Drugs Used in Covid-19 Treatment (Favipiravir and Dexamethasone) in Albino Rats, Journal of Advanced Veterinary Research, 13:10, www.advetresearch.com/index.php/AVR/article/view/1635.
4.
Almutairi et al., Liver Injury in Favipiravir-Treated COVID-19 Patients: Retrospective Single-Center Cohort Study, Tropical Medicine and Infectious Disease, doi:10.3390/tropicalmed8020129.
5.
Zhirnov et al., Favipiravir: the hidden threat of mutagenic action, Journal of microbiology, epidemiology and immunobiology, doi:10.36233/0372-9311-114.
6.
Waters et al., Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: the special case of molnupiravir, Environmental and Molecular Mutagenesis, doi:10.1002/em.22471.
7.
Hadj Hassine et al., Lethal Mutagenesis of RNA Viruses and Approved Drugs with Antiviral Mutagenic Activity, Viruses, doi:10.3390/v14040841.
8.
Shum, C., An investigational study into the drug-associated mutational signature in SARS-CoV-2 viruses, The University of Hong Kong, PhD Thesis, hub.hku.hk/handle/10722/344396.
9.
Shiraki et al., Convenient screening of the reproductive toxicity of favipiravir and antiviral drugs in Caenorhabditis elegans, Heliyon, doi:10.1016/j.heliyon.2024.e35331.
Favipiravir Observational Study Group et al., 19 Apr 2021, preprint, 1 author.
Abstract: Favipiravir Observational Study Interim Report 3
（as of February 28, 2021）
Favipiravir Observational Study Group, Fujita Health University
Late treatment
is less effective
is less effective
