Does Ivermectin Cause Sterility in 85 Percent of Men Who Use It?

Widely shared social media posts claim that ivermectin, an anti-parasitic medication that some are using to treat COVID-19 despite little evidence of efficacy, sterilizes 85 percent of men who use the drug. 

For context, the FDA has warned against using ivermectin to treat COVID-19, saying that “the FDA has not authorized or approved ivermectin for use in preventing or treating COVID-19 in humans or animals. Ivermectin is approved for human use to treat infections caused by some parasitic worms and head lice and skin conditions like rosacea.”

However, the claim that it causes male infertility is unproven. 

The claim stems from a 2011 study from Nigeria that screened 385 patients diagnosed with onchocerciasis, a parasitic disease caused by the worm Onchocerca volvulus and published in the Archives of Applied Science Research,  a self-described “peer-reviewed, open-access journal.”

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Comments (14)
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  • To say "The claim is unproven" is akin to saying that a rumored invention of a perpetual-motion machine is "unconfirmed". The first will almost certainly never be "proven", and the second, of course, will simply never be. (And let me be clear: the only reason I state that the first "will almost certainly never..." is that it's really, really hard to get me to say 'never'.)

    The "evidence" presented in support of the notion that ivermectin causes infertility in 85% of men is extremely poor, derived from a population with extremely high presence of infertility already, had small numbers, was not (meaningfully) peer-reviewed, and was not actually found in the study referenced.

    The 85% number was presented within the referenced paper as a finding from "a recent report [showing that] 85% of all male patients treated in a particular centre with ivermectin in the recent past who went to the laboratory for routine tests were discovered to have developed various forms, grades and degrees of sperm dysfunctions". The reference given is this: Asika E.C., Okhiai O., Awemu G.A. Journal of Biomedical investigation (sic); 2002: 3(1) 41-43.

    So let's take a look at that. Oh, wait, there's a problem. The Journal of Biomedical Investigation, an African journal that hasn't produced any issues since 2009, according to its website, didn't begin publication until 2003. But we've got Vol(Issue) numbers--3(1)--and page numbers, let's go there. And...Vol. 1, Issue 3, pages 41-43 is an article entitled "Antimicrobial properties of Ocimium Gratissium", by authors Chilaka, Asika, and Unekwe. Note that the surname Asika shows up in both places--and indeed, as one of the co-authors of the article originating this wild-goose chase.

    PubMed--the online scholarly database in which one looks for useful biomedical research articles and the like--finds only one published article with E. C. Asika listed as an author: Antidiarrheal and antimicrobial activities of the ethanol extract from the Icacina senegalensis root bark (J Basic Clin Physiol Pharmacol, 2018 Mar 28;29(2):211-216. doi: 10.1515/jbcpp-2016-0174) Asika's professional affiliation is given as the Department of Pharmacology and Therapeutics, Faculty of Medicine, Ebonyi State University, Abakaliki, Nigeria. The University's website gives a list of departments within the school of medicine, but nothing further.

    A quick search via ResearchGate gave eight references to published articles with Asika's name associated--none of which are the article about ivermectin and infertility that started all this, and none of which are on topics related to ivermectin/infertility.

    So...let's finish wandering in the weeds here. There's no serious suggestion of reliable or reputable claims of 85% infertility due to ivermectin. The study referenced initially looks at the paltry number of patients being treated long-term for onchocerciasis (treatment lasts many years, in most cases through the end of life) who are not at the time of screening already sterile/infertile. Let's pause here to note that while onchocerciasis isn't famous in the western scientific literature for causing sterility/infertility, but instead for being the world's #2 cause of acquired blindness (hence the name, "river blindness", given to the disease). Onchocerciasis is also known, however, amongst African natives of regions with endemic onchocerciasis, for causing infertility. And, even among the medical literature, one can find references to something called "hanging groin", in which lymphatic drainage of the groin region is so impaired that the genitalia and particularly the scrotum become massively swollen and hang down as far as the knees.

    From this, we might begin to suspect that the longer a male has onchocerciasis, the greater the risk of fertility problems due to the dermatophilic microfilaria (little itty-bitty skin worms) that cause the disease. And I'm sure we'd be right--even though such isn't frequently mentioned in western medical science publications.

    So...does ivermection cause male sterility/infertility? There's absolutely no rational reason to think so. Long history of usage suggests nothing of the sort, and there's no serious evidence it should even be looked into further.

    Just say "No."

    No, ivermectin does not cause male sterility in 85% of patients. Full stop.

    1. P.S. for those who wish to make scientific claims about what they read on the internet. What you see above is sort of a "how it's done" for the bare minimum necessary to seriously vet wild claims. Pull on the yarn and see what comes undone.

  • Unproven made me think for a second…
    “Wait…so it’s possible?!”

    Then I read the article and was like; Nah we good”

    Though reading the side effects that may cause “death”, kinda makes the low sperm thing seem more irrelevant doesn’t it?

  • You mean all I had to do was take a pill? Someone’s getting sued.

  • But it makes you want a green pasture and plenty of apples to eat.

  • If it doesn’t cause sterility, can’t we add something to it so that it will?

    *** I feel like this requires an I’m joking disclaimer. I’m joking!!!

  • How could they tell without knowing which men were sterile to start with and sending everyone who took the drug to a urologist for testing?

    In the third world, when there's a penile-related conspiracy theory, at least there's some visual clue like the penis dropping off or shriveling up.

  • Thanks for fact-checking both sides of the Ivermectin debate. It's just so tiresome and reminiscent of the debates over hydroxychloroquine last year. We get both credulous True Believers that claim they are miracle drugs, and skeptics who go too far the opposite way and assume they are poisonous substances that only crazy quacks would ever prescribe. 🙄

    But of course "the drugs aren't proven to be effective against COVID, but both have been used successfully and safely for other conditions" doesn't get as many clicks.

  • There is junk science for every occasion. It took Covid for me to realize how much of a bubble I inhabited by taking the scientific method and statistics for granted, when in actuality its just ready a claim, fire it off and then aim at a favorable study (methodology be damned) for justification...

  • Isn't ivermectin a pretty common anti-parasitic and has been for years?

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