In recent years ivermectin and fenbendazole have appeared in research on the repurposing of known drugs — testing whether a substance created for one purpose might also be useful for something else. It is a reasonable line of research, but its results are often misread and overstated. Below we set out honestly what was actually studied and how to read such reports correctly. This whole review concerns laboratory work — carried out on cells in dishes (in vitro) and in animals. These are NOT human studies.
Fenbendazole — what the cell studies described
Because fenbendazole affects the protein that builds the cell's internal “scaffolding”, it and the related mebendazole were studied in cell cultures: researchers looked at how they affect that scaffolding, cell division and sugar processing in selected cell types. These are interesting observations — but obtained under artificial conditions, in a laboratory dish rather than a living organism.
Ivermectin — what the cell studies described
Ivermectin has also been studied in cells: its effect on various intracellular processes was examined. A separate thread is the 2020 laboratory antiviral study that set off the debate around COVID-19. An important catch: it used concentrations many times higher than can safely be achieved in the human body.
The biggest problem: a dish is not a patient
The most important thing anyone reading such reports has to understand:
- An enormous difference in dose. An effect seen in a test tube often requires a dose that cannot safely be reached in a living person. What works on cells in a dish does not have to (and often simply cannot) work in a patient.
- The body is far more complex. A dish of cells has no absorption, metabolism or excretion of a drug, no immune system and no cooperation between organs.
- A mouse is not a human. Results obtained in mice very often fail to carry over to people.
Why large clinical trials are what count
Only large, carefully designed human trials — with a comparison group, and arranged so that neither the patient nor the investigator knows who receives the drug — can establish whether a substance genuinely helps people and whether it is safe. For ivermectin and COVID-19 exactly such trials (including TOGETHER and ACTIV-6) showed no meaningful benefit — despite the earlier enthusiasm based on dish studies. It is a textbook example of why one must not jump straight from the test tube to recommendations for people.
What the regulators say
Bodies such as the European EMA and the American FDA have repeatedly warned against using veterinary preparations or laboratory reagents in humans outside their official, approved uses. This is not “censoring science” — it is protecting people from hasty conclusions drawn from incomplete data.
How a researcher should approach them
For a laboratory, fenbendazole and ivermectin are valuable, well-characterised tools for studying the interior of the cell. Their real value lies in controlled experiments in a dish — not in use in humans, which the research to date simply does not justify.
Sources
- Dogra N. et al. (2018), Scientific Reports — nature.com/articles/s41598-018-30158-6
- Caly L. et al. (2020), Antiviral Research — doi.org/10.1016/j.antiviral.2020.104787
- The TOGETHER trial (2022), NEJM — nejm.org
- The ACTIV-6 trial (2022), JAMA — pubmed.ncbi.nlm.nih.gov
Educational content. These products are intended for in-vitro laboratory research only. Not for human consumption.