The use of ivermectin to treat Covid-19 has received considerable attention in the media. Ivermectin is currently approved by the US Food and Drug Administration (FDA) for the treatment of some parasitic worms (strongyloidiasis and onchocerciasis) in humans, as well as for the treatment of certain internal and external parasites in various animal species. The drug has received attention as it has been touted as an inexpensive and readily available treatment for Covid-19.

The data for the drug’s therapeutic effectiveness for treating Covid-19 have been questionable, with at least one publication retracted and several studies suspected of being fraudulent and skewing the metadata analyses performed. The FDA has not approved the use of ivermectin as a treatment for Covid-19 and the drug’s manufacturer, Merck, has released a statement that there are no data demonstrating ivermectin’s clinical activity or clinical efficacy for Covid-19 patients, along with a lack of safety data in most of the studies.

The clinical trial data for the drug show mixed results, with the larger clinical trials showing failure to achieve clinical endpoints. In the largest study, the ivermectin arm of a clinical trial for the preventive treatment for migrant workers at high risk of Covid-19 involving 4,257 enrolled subjects found no statistically significant differences compared to the oral zinc/vitamin C combination. The second largest clinical trial investigating the use of ivermectin to prevent hospitalisations in Covid-19 for 501 enrolled subjects found that there were no statistically significant differences in the safety outcomes for ivermectin versus the placebo control group.

Two of the more prominent studies supporting the efficacy of ivermectin as a treatment for Covid-19 have had their data questioned. A preprint study on the efficacy and safety of ivermectin led by Dr Ahmed Elgazzar from Benha University in Egypt was pulled due to ethical concerns over the data. An analysis of the study data showed that the wrong statistical tests had been used for some of their results, data had possibly been faked, deceased patients had been recruited after their deaths, and around 25% of the patients had been recruited before the study even started. Another influential study from Argentina by Hector Carvallo at the University of Buenos Aires has had its data called into question, with missing data, numbers of enrolled patients not matching, numbers occurring in unnatural distributions, and the hospitals where the research was supposedly carried out stating the study was not conducted there.

Preventative use of the drug to treat Covid-19 has surged in numerous Latin American countries, including Peru, Bolivia and Guatemala, and US ivermectin prescriptions have increased 24-fold, according to the US Centres for Disease Control and Prevention (CDC). In the US, people have resorted to using formulations of the drug from veterinary supply stores, resulting in overdoses. This may also be creating shortages of the drug for veterinary use. The veterinary formulations, for use in large animals such as horses and cattle, are highly concentrated, increasing risk of overdose when used by humans; this results in hypotension and neurological effects including decreased consciousness, seizure, coma and death.