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Controversial Use of Ivermectin for Treatment of COVID-19

Ivermectin, an antiparasitic drug being studied as a potential — although controversial — remedy for COVID-19, helps treat a disease that can cause vision problems but may also cause side effects involving the eyes.

In January 2021, the National Institutes of Health (NIH) noted that there wasn’t enough data to recommend or discourage use of ivermectin as a treatment for COVID-19. In 2020, the U.S. Food and Drug Administration (FDA) warned against humans taking ivermectin, intended for treatment of heartworms in animals, as a potential treatment for COVID-19.

These alerts came out as recent research indicates ivermectin had curbed reproduction of SARS-CoV-2, the virus that causes COVID-19, in a lab setting. The research, published in June 2020, didn’t involve people or animals.

Merck, the maker of ivermectin, and others have underscored the fact that no evidence thus far points to the drug being a safe or effective treatment for COVID-19. However, Merck says its scientists “continue to carefully examine the findings of all available and emerging studies of ivermectin for the treatment of COVID-19 ... .”

Merck sells ivermectin in the U.S. under the brand name Stromectol

Researchers at the University of Oxford are among those testing ivermectin as a possible COVID-19 therapy. In a letter about the large-scale Oxford study, the nonprofit Front Line COVID-19 Critical Care Alliance says that, based on its preliminary analysis of data, it believes the drug “should be the standard of care in COVID-19.”

Dr. Pierre Kory, president of the alliance, testified in December 2020 to a U.S. Senate committee about ivermectin as a COVID-19 treatment. Citing the spread of COVID-19 misinformation, YouTube subsequently pulled two videos promoting the alliance’s beliefs. Several health care experts have criticized the alliance’s analysis as weak.

A study in 2020 in Argentina indicated positive results in prevention of COVID-19 among health care workers given a combination of ivermectin and the food additive carrageenan. In Argentina and elsewhere in Latin America, over-the-counter ivermectin has become a popular but unproven COVID-19 treatment. However, many medical experts strongly caution against turning to ivermectin for self-medication, since data about its safety and effectiveness is insufficient.

While researchers in Spain conducted a small-scale test in 2020 showing promise in treating COVID-19 patients with ivermectin, they say there’s “limited evidence to support its clinical use in COVID-19 patients.”

Still, South Africa and neighboring Zimbabwe have authorized ivermectin as a COVID-19 treatment. However, South African authorities have severely restricted its use.

Dr. John Nkengasong, director of the Africa Centers for Disease Control and Prevention, told the BBC that he discourages using ivermectin for COVID-19 because the drug has yet to be tested in “controlled, clinical trials.”

SEE RELATED: Hydroxychloroquine, as coronavirus treatment, may be bad for your eyes

What is ivermectin?

Discovered in the 1970s in Japan, ivermectin has been praised as a “wonder drug” for its ability to fight diseases among people and animals. It emerged in 1988 as a treatment for a potentially vision-harming disease called onchocerciasis. 

The drug now is recognized as “one of the greatest medical accomplishments of the 20th century,” according to an article published in 2011 in a scientific journal.

How ivermectin is used

Although ivermectin hasn’t been proven as a COVID-19 treatment, it does have uses elsewhere in human health care.

Ivermectin tablets are approved for the treatment of some parasitic worms (intestinal strongyloidiasis and onchocerciasis) in people. In addition, ivermectin topical drugs are approved to treat external parasites such as head lice and skin conditions such as rosacea. Those topical treatments are also meant only for people.

Onchocerciasis, also known as river blindness, is a tropical disease caused by a parasitic worm. A river-dwelling blackfly introduces adult worms into a person’s body through repeated bites, and those produce larvae (young worms).

An onchocerciasis infection can trigger vision loss or blindness. Worldwide, river blindness is one of the most common infection-related causes of blindness.

Onchocerciasis can also lead to skin conditions such as rashes and intense itching.

The dangers of onchocerciasis

The small worms that invade someone’s body after being bitten by one of these tropical flies may infect the eye as a result of onchocerciasis, causing vision damage or even blindness. Around the world, onchocerciasis harms the vision of about 1 to 2 million people per year, about half of whom will become blind.

More than 99% of people infected by onchocerciasis live in 31 African countries. Decades-long public health campaigns have wiped out the disease in Colombia, Ecuador, Guatemala and Mexico.

Once someone is infected, he or she should take ivermectin once a year for 10 to 15 years to treat onchocerciasis. No vaccine or medication prevents the disease.

SEE RELATED: The COVID-19 vaccine: Will it affect your vision?

Side effects of ivermectin

While ivermectin can treat onchocerciasis, it also can cause side effects affecting vision. These include:

  • Sore eyes or redness

  • Puffy eyes

  • Vision problems, with loss of vision happening in rare cases

  • Unusual sensation in the eyes

  • Swollen eyelids

  • Conjunctivitis (pink eye)

  • Anterior uveitis (inflammation of the middle layer of the eye)

  • Limbitis (inflammation of the border between the cornea and the sclera, or white of the eye)

  • Keratitis, an infection of the cornea

  • Chorioretinitis or choroiditis (inflammation of the lining of the retina)

READ MORE: Follow All About Vision’s coverage of COVID-19 and how it might affect your vision.

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