Vaccine Info


Authored by
Last reviewed
December 26, 2023
Fact checked by
Robert Carlson, MD


Merck's Ivermectin (STROMECTOL®) is a U.S. Food and Drug Administration (FDA) approved semisynthetic, anthelmintic agent for oral administration. Ivermectin is derived from the avermectins, a class of highly active broad-spectrum, antiparasitic agents isolated from the fermentation products of Streptomyces avermitilis. Ivermectin is a mixture containing at least 90% 5-Odemethyl-22,23-dihydroavermectin A1a and less than 10% 5-O-demethyl-25-de(1-methylpropyl)-22,23-dihydro25-(1-methylethyl)avermectin A1a, generally referred to as 22,23-dihydroavermectin B1a and B1b, or H2B1a and H2B1b, respectively

On March 6, 2023, the U.S. Food and Drug Administration (FDA) confirmed Ivermectin is an approved antiparasitic drug used to treat several neglected tropical diseases, including onchocerciasis, helminthiases, scabies, and strongyloidiasis and onchocerciasis, two conditions caused by parasitic worms. Ivermectin has been widely used for these indications and is generally well tolerated. Ivermectin is usually well tolerated when used in appropriate doses for approved indications. The FDA disapproves Ivermectin for the treatment of any viral infection. The U.S. Centers for Disease Control and Prevention (CDC) issued Health Alert Network Health Advisory CDCHAN-00463 on April 25, 2022, updating healthcare providers, public health departments, and the public about the availability and use of recommended therapies for COVID-19.

On February 18, 2023, the JAMA Network published an Original Investigation: a double-blind, randomized, placebo-controlled platform phase 3 clinical trial including 1206 US adults with COVID-19 from February 2022 to July 2022, the median time to sustained recovery was 11 days in the ivermectin group and 11 days in the placebo group. In this primarily vaccinated (84%) population, the posterior probability that Ivermectin reduced symptom duration by more than one day was less than 0.1%. These findings do not support the use of Ivermectin among outpatients with COVID-19.

Ivermectin Indication

The U.S. CDC says Ivermectin is indicated to treat the following infections: Strongyloidiasis of the intestinal tract. Ivermectin is indicated for treating intestinal (i.e., nondisseminated) strongyloidiasis due to the nematode parasite Strongyloides stercoralis. This indication is based on clinical studies of comparative and open-label designs, in which 64-100% of infected patients were cured following a single 200-mcg/kg dose of Ivermectin.

In addition, some topical forms of Ivermectin are approved to treat external parasites like head lice and skin conditions such as rosacea. Zydus Lifesciences Limited (formerly Cadila Healthcare Limited) received final approval from the USFDA to market Ivermectin Cream, 1%, Soolantra. Ivermectin Cream is used for the treatment of inflammatory lesions of rosacea. Soolantra will be manufactured at the group's topical manufacturing facility in Ahmedabad, India.

Ivermectin is contraindicated for those five years of age or those weighing less than 15 kilograms and individuals with liver or kidney disease.

Ivermectin COVID-19

Merck, the manufacturer of Ivermectin, stated in February 2021 that there is insufficient evidence to support using Ivermectin to treat COVID-19. Ivermectin is not authorized or approved by the U.S. FDA to prevent or treat COVID-19. In 2021, the FDA published: Why You Should Not Use Ivermectin to Treat or Prevent COVID-19.

A peer-reviewed study published by the JAMA Network on February 20, 2023, concluded these findings do not support using Ivermectin among outpatients with COVID-19. In addition, the U.S. National Institutes of Health's COVID-19 Treatment Guidelines Panel determined on February 11, 2021, that there is currently insufficient data to recommend Ivermectin for the treatment of COVID-19. On October 19, 2021, the Canadian government issued a notice saying, 'Ivermectin is not authorized to prevent or treat COVID-19 and may cause serious health problems.' The WHO recommendation concerning Ivermectin was published on 31 March 2021 as the fourth version of the WHO living guideline and in the BMJ as Rapid Recommendations.

Lawyers representing the FDA wrote in their motion (Case 3:22-cv-00184 Document 25 Filed on 08/26/22 in TXSD) to dismiss a legal case: "They 'neither require[d] nor forb[ade] any action on the part of' Plaintiffs or anyone else." The FDA's description in court of its posts as recommendations didn't constitute a change in the U.S. administration's position.

Studies published in 2022 for mild to moderate illnesshospitalization, or time to recovery from the nonsevere disease have not found Ivermectin use to be effective. A study published in 2020 found to have broad-spectrum antiviral activity in vitro, is an inhibitor of the causative virus (SARS-CoV-2), with a single addition to Vero-hSLAM cells 2 h post-infection with SARS-CoV-2 able to effect ~5000-fold reduction in viral RNA at 48 hours.

Ivermectin Dengue

Ivermectin has been previously shown to inhibit all four dengue serotypes in vitro by inhibiting the host nuclear import proteins that were important for nuclear localization of the dengue NS5 protein with RNA-dependent RNA polymerase (RdRp) function. A phase 2/3 randomized, double-blind, placebo-controlled trial (NCT02045069) was conducted to study the efficacy of a once-daily dose of Ivermectin 400 μg/kg for 2–3 days in adult dengue patients. Interestingly, the study reported faster NS1 antigenemia clearance upon ivermectin treatment, with no difference in viremia, viral clearance, or any beneficial clinical outcomes, including fever, DHF incidence, hospitalization, pleural effusion, hemoconcentration, or fluid requirements.

Ivermectin Malaria

The Lancet published results from a study published in 2019 that stated Ivermectin is widely used in mass drug administrations for controlling neglected parasitic diseases and can be lethal to malaria vectors that bite-treated humans. Therefore, it could be a new tool to reduce plasmodium transmission. The primary analysis of this study showed that the mean number of clinical malaria episodes per child was about 20% lower in the intervention group than in the control group over the 18-week treatment period. Study Interpretation: Frequently repeated mass administrations of Ivermectin during the malaria transmission season can reduce malaria episodes among children without significantly increasing harm to the populace.

Ivermectin COVID-19 Meta-Analysis

The Ivermectin for COVID-19 real-time meta-analysis of 95 studies was updated on February 23, 2023.

Ivermectin Vs. American Medical Association

In a case before the Wisconsin Supreme Court, the American Medical Association and Wisconsin Medical Society filed an amicus brief on December 7, 2022, arguing against Ivermectin as a court-ordered intervention for COVID-19 as the drug has not proven effective against the disease.

Ivermectin Use Against Human Adenoviruses

Human adenoviruses (HAdVs) are ubiquitous and clinically essential pathogens without an effective antiviral treatment. HAdV infections typically cause mild symptoms; however, individuals such as children, those with underlying conditions, and those with compromised immune systems can develop severe disseminated disease. Our study results demonstrate that Ivermectin, an FDA-approved antiparasitic agent, effectively inhibits the replication of several HAdV types in vitro.

Ivermectin Overdose Adverse Effects 

The U.S. CDC reported on August 26, 2021, that ivermectin side effect calls had increased sharply, to a five-fold increase from baseline. These reports are also associated with increased frequency of adverse effects and emergency department/hospital visits; gastrointestinal symptoms such as nausea, vomiting, and diarrhea; Low blood pressure (hypotension); Neurologic effects such as decreased consciousness, confusion, hallucinations, central nervous system depression, seizures, coma, and death.

Ivermectin Revenues 2021

The JAMA Network published a Letter on January 13, 2022 - U.S. Insurer Spending on Ivermectin Prescriptions for COVID-19. Insurer spending, estimated at $2.5 million on August 13, 2021, would extrapolate to $129.7 million annually. The amount of waste is even higher because estimates did not include Medicaid spending.

Ivermectin News 2021 - 2023

March 21, 2023 - The U.S. FDA issued a Notice of Unlawful Sale of Unapproved and Misbranded Drugs to United States Consumers Over the Internet.

December 7, 2022 - The AMA announced: "The overwhelming majority of studies investigating Ivermectin have not found it an effective COVID-19 treatment. The few dissenting studies that exist have 'substantially evaporated under scrutiny, and even Ivermectin's manufacturer 'do[es] not believe that the data available support the safety and efficacy of Ivermectin for preventing or treating COVID-19. Thus, the consensus view of reasonable medical providers is that, apart from clinical trials, Ivermectin should not be administered to treat COVID-19."

October 21, 2022 - The JAMA Network published an Original Investigation: Effect of Ivermectin vs. Placebo on Time to Sustained Recovery in Outpatients With Mild to Moderate COVID-19. Among outpatients with mild to moderate COVID-19 in a phase 3 study, treatment with Ivermectin, compared with placebo, did not significantly improve the time to recovery. Therefore, these findings do not support using Ivermectin in patients with mild to moderate COVID-19.

August 31, 2022 - An ORIGINAL ARTICLE, PEER-REVIEWED: Regular Use of Ivermectin as Prophylaxis for COVID-19 Led Up to a 92% Reduction in COVID-19 Mortality Rate in a Dose-Response Manner: Results of a Prospective Observational Study of a Strictly Controlled Population of 88,012 Subjects. Conclusion - Non-use of Ivermectin was associated with a 12.5-fold increase in mortality rate and a seven-fold increased risk of dying from COVID-19 compared to the regular use of Ivermectin.

July 11, 2022 - The journal Frontier published a HYPOTHESIS AND THEORY article: Microbiome-Based Hypothesis on Ivermectin's Mechanism in COVID-19: Ivermectin Feeds Bifidobacteria to Boost Immunity. 'We hypothesize that Ivermectin, as a by-product of Streptomyces fermentation, can feed Bifidobacterium.'

June 12, 2022 - A non-peer-review study published by the ACTIV-6 Study Group - Conclusions: Ivermectin dosed at 400 mcg/kg daily for three days in a phase 3 clinical trial resulted in less than one day of shortening of symptoms and did not lower the incidence of hospitalization or death among outpatients with COVID-19 in the U.S. during the delta and omicron variant time periods.

June 7, 2022 - Missouri House Bill 2149 bars medical licensing boards from punishing doctors who lawfully prescribe Ivermectin.

May 6, 2022 - The peer-reviewed journal The Lancet published a study that compared the effectiveness of mass drug administration with the triple-drug and two-drug regimens for reducing microfilariae prevalence to less than 1% and circulating filarial antigen prevalence to less than 2%, levels that are unlikely to sustain transmission of lymphatic filariasis, in Papua New Guinea. Interpretation: This clinical study found mass administration of the triple-drug regimen was more effective than the two-drug regimen in reducing microfilariae prevalence in communities to less than the target level of 1% but did not reduce circulating filarial antigen prevalence to less than 2%.

April 26, 2022 - Tennessee bill HB2746/SB2188, sponsored by Representative Susan Lynn (R-Mt. Juliet-D57) and Senator Frank Niceley (R-Strawberry Plains-D8), allows pharmacists to prescribe Ivermectin to patients while protecting a pharmacist or doctor from being liable for the prescription.

March 30, 2022 - The NEJM published an Original Investigation: Effect of Early Treatment with Ivermectin among Patients with Covid-19 - This phase 3 study concluded that 'Treatment with Ivermectin did not result in a lower incidence of medical admission to a hospital due to progression of Covid-19 or prolonged emergency department observation among outpatients with an early diagnosis of Covid-19.

March 18, 2022 - The WSJ reported: "There was no indication that ivermectin is clinically useful," said Edward Mills, a professor of health sciences at Canada's McMaster University in Hamilton, Ontario. Dr. Mills plans to present the findings at a public forum sponsored by the National Institutes of Health.

March 7, 2022 - Science Direct published the results of an analysis of the difference in mortality of patients treated with Ivermectin vs. patients treated with remdesivir with COVID-19 in the United States using TriNetX Research network, a federated EMR network of over 44 healthcare organizations and 68 million U.S. patients. The conclusion showed Ivermectin use was associated with decreased mortality in patients with COVID-19 compared to remdesivir. To our knowledge, this is the most extensive association study of patients with COVID-19, mortality, and Ivermectin.

February 18, 2022 - In an original investigation, Jama Network reported on an open-label randomized clinical trial of high-risk patients with COVID-19 in Malaysia. The authors said that Ivermectin in this setting did not reduce the risk of developing the severe disease compared with the standard of care alone.

January 31, 2022 - India Today reported Japan's Kowa Co Ltd. says Ivermectin is effective against Omicron in the phase III trial. The study named Corvette-01 is a Phase 2 study with 240 participants.

January 26, 2022 - Reuters Fact Check published an update on home COVID-19 care kits the Mexican government delivered that contain Ivermectin. In 2021 ivermectin was distributed by the Mexican Institute of Social Security (IMSS), the kits included Ivermectin, aspirin, paracetamol, and azithromycin, as well as face masks and an oximeter. However, starting January 4, 2022, the IMSS has stopped including Ivermectin in the home care kits.

January 19, 2022 - New Hampshire lawmakers are trying to allow pharmacists to dispense Ivermecting using standing orders.

January 15, 2022 - An observational study of 223,128 people revealed that regular use of Ivermectin as a prophylactic agent was associated with significantly reduced COVID-19 infection, hospitalization, and mortality rates. The details of this study can be found here.

November 26, 2021 - The WHO recently reported: "Despite pandemic challenges, health workers managed to deliver ivermectin treatment to more than 112 million people," stated Dr. Daniel Argaw Dagne, Unit Head, Prevention, Treatment and Care, WHO Department of Control of Neglected Tropical Diseases.

November 23, 2021 - Medpage Today published the results of a pilot trial. The idea was to fill bird feeders with ivermectin-treated bird feed to see if this treated bird feed would reduce the number of infectious mosquitoes that could transmit the West Nile virus to humans. Karen Holcomb, Ph.D., of the University of California Davis, hypothesized that because Ivermectin had mosquitocidal properties and low toxicity in mammals and birds, it might be possible to treat bird-feeders with Ivermectin, where the mosquitoes would bite the birds, ingest the Ivermectin, and die before the virus could be transmitted to humans.

November 18, 2021 - Medpage Today published an article discussing the significant progress against the transmission of onchocerciasis, or river blindness, in several Nigerian states. Mass drug administration of Ivermectin is being credited for this progress.

October 20, 2021 - The NEJM published a Correspondence: Toxic Effects from Ivermectin Use Associated with Prevention and Treatment of Covid-19. Cases in Oregon illustrate the potentially toxic effects of Ivermectin, including severe episodes of confusion, ataxia, seizures, and hypotension, and the increasing frequency of inappropriate use. In addition, there is insufficient evidence to support the use of Ivermectin to treat or prevent COVID-19, and improper use and the possible occurrence of medication interactions may result in serious side effects requiring hospitalization.

October 18, 2021 - The Lancet Infectious Diseases published: Long-term consequences of misusing ivermectin data. 

October 4, 2021 - The Royal Society of Chemistry published its paper on the microscopic interactions between Ivermectin and key human and viral proteins involved in SARS-CoV-2 infection. 

October 1, 2021 - The Onchocerciasis Elimination Program for the Americas (OEPA) was created at the end of 1993 to eliminate onchocerciasis from the Americas. Its objectives are to provide technical and supplemental financial assistance to the elimination programs of the six endemic countries: Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela, according to an analysis in 2020 of administrative units that had achieved at least 20 cumulative rounds of ivermectin treatment and coverage of at least 85% of the eligible population.

September 24, 2021 - The Indian Council of Medical Research dropped Ivermectin from the approved COVID-19 treatment protocol. 

September 9, 2021 -  In an episode of "AMA COVID-19 Update," Dr. Farley discussed the drug's safety concerns, potential side effects, and the vital role of physicians in guiding the unvaccinated to better choices.

September 3, 2021 - The U.S. FDA published Why You Should Not Use Ivermectin to Treat or Prevent COVID-19.

August 26, 2021 - The U.S. CDC issued a Health Advisory stating a rapid Increase in Ivermectin Prescriptions and Reports of Severe Illness Associated with the Use of Products Containing Ivermectin to Prevent or Treat COVID-19.

August 24, 2021 - Oregon Poison Center at OHSU experiences a substantial increase in calls involving intentional misuse of Ivermectin.

August 13, 2021 - Frontiers in Pharmacology published a research paper discussing a new application of Ivermectin. These researchers were able to demonstrate that the use of Ivermectin inhibited colorectal cancer cell growth. "In conclusion, we have demonstrated that Ivermectin may regulate the expression of crucial molecules Caspase-3, Bax, Bcl-2, PARP, and Cleaved-PARP in the apoptosis pathway by increasing ROS production and inhibiting the cell cycle in the S phase to inhibit colorectal cancer cells. Therefore, current results indicate that Ivermectin might be a new potential anticancer drug for treating human colorectal cancer and other cancers."

June 2021 - The American Journal of Therapeutics published a review of the Emerging Evidence Demonstrating the Efficacy of Ivermectin in the Prophylaxis and Treatment of COVID-19. "In summary, based on the totality of the trials and epidemiologic evidence presented in this review, along with the preliminary findings of the Unitaid/WHO meta-analysis of treatment RCTs and the guideline recommendation from the international BIRD conference, ivermectin should be globally and systematically deployed in the prevention and treatment of COVID-19."

January 20, 2021 - Nature published results identifying 3-chymotrypsin-like protease (3CLPro) inhibitors as potential anti-SARS-CoV-2 agents. Ivermectin exhibited complete inhibition of SARS-CoV-2 3CLpro enzymatic activity, blocking viral replication of SARS-CoV-2 by more than 80%.

April 27, 2018 - A systematic literature review and meta-analysis on the efficacy and safety of ivermectin-albendazole co-administration in five different databases (i.e., PubMed, ISI Web of Science, ScienceDirect, CENTRAL, and from 1960 to January 2018.

May 10, 2015 - The Nobel Assembly at Karolinska Institutet has today decided to award the 2015 Nobel Prize in Physiology or Medicine with one-half jointly to William C. Campbell and Satoshi Ōmura for their discoveries concerning a novel therapy against infections caused by roundworm parasites.

Ivermectin Clinical Trials

Ivermectin (Stromectol, Mectizan) has been tested in over 190 clinical trials, including 78 studies using Ivermectin to treat COVID-19.