The Antiparasitic Drug Ivermectin Is No “Silver Bullet” for COVID-19, Current Evidence Shows

A number of prevention strategies, including social distancing, wearing face coverings and taking one of the three COVID-19 vaccines that have been approved or authorized by the Food and Drug Administration (FDA), are effective for reducing the spread of COVID-19. So far, though, the FDA has approved just a single antiviral medication, remdesivir (VEKLURY), for treating COVID-19 in hospitalized patients only.[1]

The FDA has neither approved nor authorized ivermectin (an antiparasitic drug) for COVID-19 infection and, importantly, posted material on its website that recommends against its use for this purpose.[2]

Yet, dispensed prescriptions of ivermectin from U.S. outpatient retail pharmacies have increased by more than 24-fold as of Aug. 13, 2021, compared with the number of these prescriptions before the pandemic, according to a recent advisory issued by the Centers for Disease Control and Prevention (CDC).[3] This surge in ivermectin use is believed to largely be due to the relentless promotion and misinformation disseminated by certain celebrities and fringe groups on social media and other outlets.[4], [5]

This article summarizes the current evidence on ivermectin, which does not support its use for COVID-19 infection.

About ivermectin

In terms of human use, the FDA has approved a single small dose (up to 200 micrograms per kilogram) of the tablet form of ivermectin (STROMECTOL) to treat two types of infections by roundworm parasites, which are uncommon in the U.S.: intestinal strongyloidiasis and onchocerciasis (river blindness).[6]

The agency also approved a topical over-the-counter lotion (SKLICE)[7] form of ivermectin for treating head lice and a prescription cream (SOOLANTRA)[8] form for treating skin lesions caused by rosacea.

The FDA also has approved other formulations of ivermectin to treat certain internal and external parasites in various animal species.[9] Notably, the agency advised that consumers should never take animal drugs that contain ivermectin for any reason because the agency has only evaluated their use in the species for which they are approved. It also cautioned that such animal drugs can cause major harm in humans.

No good evidence of effectiveness for COVID-19

In April 2020, an Australian study showed that ivermectin inhibits the replication of SARS-CoV-2 (the virus that causes COVID-19) in a laboratory dish (not in humans).[10] This type of study is commonly used in the earliest stages of antiviral-drug testing. In fact, achieving ivermectin blood concentrations in humans similar to those used in the laboratory study would require using doses up to 100-fold higher than those approved for use in humans,[11] which would be too toxic.

Since then, there have been several completed and ongoing studies on the use of ivermectin in COVID-19 patients.[12] However, most of these studies are small and are plagued by significant methodological weaknesses, which downgrades their strength, according to the National Institutes of Health COVID-19 Treatment Guidelines Panel. Therefore, in July 2021, the Panel concluded that there is insufficient evidence to recommend either for or against the use of ivermectin for treating COVID-19.[13]

Similarly, researchers from the Cochrane Research Collaboration, an independent nonprofit organization, reviewed evidence from randomized controlled trials (the gold-standard studies in medical research) that compared ivermectin to no treatment, placebo or usual care in COVID-19 subjects.[14] Based on findings from 14 completed trials (enrolling 1,678 subjects collectively) that had been published by May 2021, the Cochrane researchers concluded that the current evidence is low and does not support the use of ivermectin for treatment or prevention of COVID-19 in the real world.

Consequently, unless there is evidence from large, well-designed and well-conducted controlled clinical trials to support the use of ivermectin in COVID-19 patients, it is best to avoid using the drug for this purpose.

Safety concerns

Although standard approved doses of ivermectin for parasitic infections are generally safe,[15] severe adverse effects including ataxia (loss of coordination) and seizures have occasionally been reported.[16] In contrast, ivermectin’s safety for COVID-19 prevention and treatment has not been established.[17]

Ivermectin’s label mentions that people who take inappropriately high doses of ivermectin can experience toxic effects.[18] Notably, the increase of ivermectin use as of July 2021 has coincided with a fivefold rise in the number of calls to U.S. poison control centers due to human exposures to ivermectin compared with the number of such calls before the pandemic.[19] This surge in calls also coincides with an increased number of reported adverse effects as well as emergency department and hospital visits related to ivermectin.

Particularly, the CDC warned consumers that ivermectin products purchased without a prescription, including topical formulations and products intended for use in large animals (such as cattle and horses), can be very concentrated and can cause overdoses if ingested. The agency also cautioned that animal ivermectin products contain inactive ingredients that have not been evaluated for human use.

Importantly, ivermectin can increase the effects of certain drugs, including those that depress the central nervous system (such as barbiturates and benzodiazepines) and the blood-thinner drug warfarin (COUMADIN, JANTOVEN).[20]

What You Can Do

Do not use any form of ivermectin to prevent or treat COVID-19. Particularly, do not swallow topical ivermectin products and those that are not intended for human use.

If you need to take ivermectin for an approved use (to treat a parasitic infection), do so under the care of a licensed doctor, obtain the drug from a legitimate source and take it as prescribed.

Seek immediate medical attention or call the poison control center hotline (800-222-1222) if you have taken ivermectin or a product that contains ivermectin and are having adverse effects. These reactions can involve the cardiovascular system (such as fast heart rate and low blood pressure), the central nervous system (such as blurred vision, confusion, decreased alertness, dizziness, hallucinations, headache, loss of coordination and balance, seizures, tremors and even coma) or the gastrointestinal system (such as abdominal pain, diarrhea, nausea and vomiting).

The best way to protect yourself and others from COVID-19 infection is by taking prevention measures, such as wearing a proper face covering and frequent handwashing, as well as getting vaccinated against COVID-19.

Report anyone claiming to have an unauthorized drug or product to prevent or cure COVID-19 to the FDA by calling 888-INFO-FDA.
 

References

[1] Food and Drug Administration. Know your treatment options for COVID-19. July 30, 2021. https://www.fda.gov/consumers/consumer-updates/know-your-treatment-options-covid-19. Accessed November 3, 2021.

[2] Food and Drug Administration. Why you should not use ivermectin to treat or prevent COVID-19. 2021. September 3, 2021. https://www.fda.gov/consumers/consumer-updates/why-you-should-not-use-ivermectin-treat-or-prevent-covid-19. Accessed November 3, 2021.

[3] Centers for Disease Control and Prevention (CDC). CDC health advisory. Rapid increase in ivermectin prescriptions and reports of severe illness associated with use of products containing ivermectin to prevent or treat COVID-19. August 26, 2021. https://emergency.cdc.gov/han/2021/pdf/CDC_HAN_449.pdf. Accessed November 3, 2021.

[4] Lind JN, Lovegrove MC, Geller AI, et al. Increase in outpatient ivermectin dispensing in the US during the COVID-19 pandemic: A cross-sectional analysis. J Gen Intern Med. 2021;36(9):2909-2911.

[5] Centers for Disease Control and Prevention. COVID-19 state of vaccine confidence insights report #15. September 27, 2021. https://www.cdc.gov/vaccines/covid-19/downloads/SoVC-report15.pdf. Accessed November 3, 2021.

[6] Merck Sharp & Dohme Corp. Label: ivermectin (STROMECTOL). February 2018. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=681888c9-af79-4b7d-ae80-c3f4f6f1effd&type=display/. Accessed November 3, 2021.

[7] Arbor Pharmaceuticals. Label: ivermectin (SKLICE). May 2021. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/202736Orig1s009lbl.pdf. Accessed November 3, 2021.

[8] Galderma Laboratories, L.P. Label: ivermectin (SOOLANTRA). July 2018. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=b1d5b166-ab06-4ab5-b0c6-31126238118a&type=display. Accessed November 3, 2021.

[9] Food and Drug Administration. FAQ: COVID-19 and ivermectin intended for animals. April 26, 2021. https://www.fda.gov/animal-veterinary/product-safety-information/faq-covid-19-and-ivermectin-intended-animals. Accessed November 3, 2021.

[10] Caly L, Druce JD, Catton MG, et al. The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitro. Antivir Res. 2020;178(June):104787.

[11] National Institutes of Health. COVID-19 treatment guidelines. Ivermectin. February 11, 2021. https://www.covid19treatmentguidelines.nih.gov/therapies/antiviral-therapy/ivermectin/. Accessed November 3, 2021.

[12] Ibid.

[13] National Institutes of Health. COVID-19 treatment guidelines. Antiviral drugs that are approved or under evaluation for the treatment of COVID-19. July 8, 2021. https://www.covid19treatmentguidelines.nih.gov/therapies/antiviral-therapy/summary-recommendations/. Accessed November 3, 2021.

[14] Popp M, Stegemann M, Metzendorf MI, et al. Ivermectin for preventing and treating COVID-19. Cochrane Database Syst Rev. 2021;7(7):CD015017.

[15] Covid-19 and ivermectin: many trials, few results, no proven efficacy. Prescrire in English. February 13, 2021.

[16] Garegnani LI, Madrid E, Meza N. Misleading clinical evidence and systematic reviews on ivermectin for COVID-19. BMJ Evid Based Med. doi: 10.1136/bmjebm-2021-111678. Published online ahead of print April 22, 2021.

[17] Popp M, Stegemann M, Metzendorf MI, et al. Ivermectin for preventing and treating COVID-19. Cochrane Database Syst Rev. 2021;7(7):CD015017.

[18] Merck Sharp & Dohme Corp. Label: ivermectin (STROMECTOL). February 2018. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=681888c9-af79-4b7d-ae80-c3f4f6f1effd&type=display/. Accessed November 3, 2021.

[19] Centers for Disease Control and Prevention. CDC health advisory. Rapid increase in ivermectin prescriptions and reports of severe illness associated with use of products containing ivermectin to prevent or treat COVID-19. August 26, 2021. https://emergency.cdc.gov/han/2021/pdf/CDC_HAN_449.pdf. Accessed November 3, 2021.

[20] IBM Micromedex. Drug interactions. http://www.micromedexsolutions.com/home/dispatch. Search term: “ivermectin.” Accessed November 3, 2021.