On September 7 2021, a meme claiming “ivermectin causes male infertility” was shared to Imgur, quickly going viral on other platforms as well:
Under the top text (“ivermectin causes male infertility,”) additional bottom text read:
Sh …. Don’t tell those that are taking it. It’s another way of thinning the (ahem) herd.
Google Trends data showed a spike in searches for “ivermectin infertility” on September 7 2021. Related searches included “ivermectin causes infertility,” and “does ivermectin cause infertility in humans?”
At the time the meme was shared, ivermectin had become a widespread topic of discourse as a purported possible treatment for COVID-19. Food and Drug Adminstration (FDA) guidance updated on September 3 2021, “Why You Should Not Use Ivermectin to Treat or Prevent COVID-19,” began:
COVID-19. We’ve been living with it for what sometimes seems like forever. Given the number of deaths that have occurred from the disease, it’s perhaps not surprising that some consumers are turning to drugs not approved or authorized by the Food and Drug Administration (FDA).
One of the FDA’s jobs is to carefully evaluate the scientific data on a drug to be sure that it is both safe and effective for a particular use. In some instances, it can be highly dangerous to use a medicine for the prevention or treatment of COVID-19 that has not been approved by or has not received emergency use authorization from the FDA.
There seems to be a growing interest in a drug called ivermectin for the prevention or treatment of COVID-19 in humans. Certain animal formulations of ivermectin such as pour-on, injectable, paste, and “drench,” are approved in the U.S. to treat or prevent parasites in animals. For humans, ivermectin tablets are approved at very specific doses to treat some parasitic worms, and there are topical (on the skin) formulations for head lice and skin conditions like rosacea.
However, the FDA has received multiple reports of patients who have required medical attention, including hospitalization, after self-medicating with ivermectin intended for livestock … The FDA has not authorized or approved ivermectin for the treatment or prevention of COVID-19 in people or animals. Ivermectin has not been shown to be safe or effective for these indications.
The FDA further explained that approval for animal usage differed from that in humans:
Never use medications intended for animals on yourself or other people. Animal ivermectin products are very different from those approved for humans. Use of animal ivermectin for the prevention or treatment of COVID-19 in humans is dangerous.
Nothing in the FDA’s document about ivermectin and its folk-medicine usage at the time mentioned infertility. However, the Imgur submitter linked to an article published in the journal Andrology in late 2017.
“Andrology” in the context of the journal is a medical discipline concerning, in its own words, “male health, particularly relating to the problems of the male reproductive system and urological problems that are unique to men.” The article was titled “Effects of ivermectin and its combination with alpha lipoic acid on expression of IGFBP-3 and HSPA1 genes and male rat fertility,” and its summary read:
This study was conducted to evaluate the effects of ivermectin (IVM) with therapeutic dose (injected with 0.56 mg/kg b.wt.) either alone or combined with alpha lipoic acid (ALA) (50 mg/kg b.wt daily) on expression of testicular insulin-like growth factor binding protein-3 (IGFBP-3) and heat-shock protein A1 (HSPA1)) genes in the testes, as well as on male rat fertility parameters. Results revealed that expression levels of IGFBP-3 and HSPA1 were significantly increased in testis of the IVM-treated group relative to the control group. Furthermore, injection of ivermectin showed a significant decrease in serum testosterone level, sperm count, motility %, live sperm% and index weight of reproductive organs, and a significant increase in sperm abnormalities. Moreover, IVM induced oxidative stress and pathological alterations in the testes. Meanwhile, the administration of ALA with IVM prevented testicular damage and improved all previous parameters. We concluded that ivermectin has undesirable effects on male fertility and altered expression of IGFBP-3 and HSPA1 genes in the testes, while the administration of alpha lipoic acid can ameliorate the adverse effects of ivermectin.
Searches for whether ivermectin caused male infertility also led to research published in November 2019, titled “The effect of ivermectin® on fertility, fecundity and mortality of Anopheles arabiensis fed on treated men in Ethiopia.” However, “Anopheles arabiensis” was a species of mosquito, and the publication in question was Malaria Journal.
Likewise, research published in September 2008 carried what appeared to be a relevant headline; the second portion again referenced animal populations: “Effect of ivermectin on male fertility and its interaction with P-glycoprotein inhibitor (verapamil) in rats.”
More recent to the meme was a September 2021 Wonkette item, “Paste Eaters Beware: Ivermectin Is Coming For Your Sperms.” It read in part:
All of this incredible “critical thinking” got me thinking. How is the horse paste these dopes are gobbling up affecting their fertility? Because boy, wouldn’t that be quite a twist. So I googled Ivermectin and sperm count and wouldn’t you know it … there are several studies, dating back years, suggesting that Ivermectin lowers sperm count and sperm motility. Most of them have to do with animals (unsurprisingly), but one did analyze the effects of Ivermectin on the sperm count of men using it to treat onchocerciasis, or “river blindness.”
From a 2011 study on Ivermectin and sperm count in humans:
For normal fertilization to occur the sperm functions must meet the minimum required sperm functional capacity as shown in table 1 which serve as normal control in this study. From the results obtained, it is evident that ivermectin therapy has significant adverse effects on the sperm functions of male onchocerciasis patients so treated. There was a significant reduction or drop in the sperm counts of the patients after their treatment with ivermectin. Furthermore, the study showed a significant and remarkable drop in the sperm motility of the patients after their treatment with ivermectin. As for the morphology of the sperm, there was a rise in the abnormal sperms after treatment compared with the morphology before the commencement of treatment. These changes no doubt are as results of the effects of the drug on the sperm function of the patients.
Although, there were no noticeable changes in the sperm volumes, sperm viscosity and the sperm liquefaction time the results of this study is enough to cause infertility in these patients.
This is similar to the findings of Tanyıldızı and Bozkurt in animals, thus, they recommended caution in the use of ivermectin in animals met for breeding.
Wonkette cited research [PDF] published in 2011 in the Archives of Applied Science Research, “Effects of Ivermectin therapy on the sperm functions of Nigerian onchocerciasis patients.” An abstract indicated some effects on sperm motility and semen viscosity, recommending caution be exercised to avoid potential “adverse effects” of ivermectin on male fertility:
The effect of ivermectin, a broad spectrum antihelminthic on the sperm functions of animal models have been extensively studied, however data on humans are very scanty hence this present study. In this study we screened a total of 385 patients who were diagnosed of onchocerciasis. Out of which, 37 (9.6%) were eligible for further tests, as their sperm counts were normal while the remaining patients had very low sperm counts and were therefore not used for further tests or were too weak after the preliminary screening tests and were not considered eligible for further test/studies. We therefore investigated the effects of ivermectin therapy on the sperm functions of these eligible 37 diagnosed patients of onchocerciasis who were of ages between 28 and 57 years. The sperm functions were assessed via seminal fluid analysis using standard procedure and the following parameters were measured: sperm counts, sperm motility, sperm morphology, sperm volume, sperm viscosity and sperm liquefaction time. The above parameters were measured before and after the patients were treated with 150µg/kg body wt of ivermectin for eleven months and the results were compared and also with normal control reference range. We observed significant reduction in the sperm counts and sperm motility of the patients tested. On the morphology there was significant increase in the number of abnormal sperm cells. This took the forms of two heads, double tails, white (albino) sperms and extraordinarily large heads. It is suspected that the above alterations in the already determined parameters of the patients’ sperm cells could only have occurred as a result of their treatment with ivermectin. However, we could not record any significant change or alteration in the sperm viscosity, sperm volume, and sperm liquefaction time of the patients. We therefore suggest that caution be seriously exercised in the treatment of male onchocerciasis patients with ivermectin to avoid the adverse effects it has on the patients’ sperm functions.
Wonkette described the paper as “ample evidence that Ivermectin causes infertility in men,” but the paper was brief and did not seem to address factors such as the duration of fertility effects on patients, if any. A Reddit user shared a link to the paper to r/Coronavirus, where a top-level comment observed from a layperson’s reading:
This paper isn’t great, it’s very poor. Not that it’s incorrect but it’s lacking the scientific rigor which is normally necessary to make the conclusions they’re claiming. Honestly, they didn’t even have a control group of people who had onchocerciasis and didn’t take ivermectin. And it seems like 90% of the patients that were pre-screened and not included in the study (I’m assuming before given ivermectin) already had deficits with their sperm?! Who is to say that onchocerciasis affects your sperm health and not ivermectin?
Another commenter responded:
Come on guys… random research team in Nigeria with a cohort of subjects that have river blindness and god knows what other variables, with less than 400 in the study.
This is the same reaching ivermectin users do.
A popular Imgur meme claimed ivermectin caused male infertility, citing a study concerning mosquitos, not humans. A single study from 2011 attempted to determine whether ivermectin affected male fertility, but the scope and findings were limited. As indicated early on, a lack of evidence or indication of efficacy were reason enough not to take ivermectin (particularly ivermectin formulated for livestock rather than people) as a treatment or preventive measure for COVID-19. Evidence that ivermectin causes male infertility was, as the single paper noted, “scanty.”