This is possibly true especially if one is high in body fat. Ivermectin's half life is quite long. But ivermectin metabolites can have biological impact in the body for a month or longer, even after one dose. So I could definitely see something like a few weeks supplementation having biological effects for potentially months.My doctor said something to that effect...that you're supposed to cycle it. Apparently, the IVM you take in one cycle will protect you for another 6 months after the cycle without you having to take another pill during that time.
https://pubmed.ncbi.nlm.nih.gov/19069991/ - One other reason to be cautious with long-term dosing protocols. This study shows potentially adverse effects of ivermectin on fertility. However, the study parameters were very high dosages, something far beyond what we would be taking. Nonetheless, given ivermectin has the tendency to build up in the body (in fat cells), we have to be careful that overtime the bioactive components do not add up and begin to influence fertility.