Ivermectin is a drug for humans and animals to treat internal and external parasites -- including certain types of worms, fleas, ticks and lice.

In humans ivermectin tablets are U.S. Food and Drug Administration-approved for treatment of some parasitic worms. Some topical formulations are FDA-approved for the treatment of external parasites like head lice and skin conditions such as rosacea.

In animals ivermectin is FDA-approved for prevention of heartworm disease in dogs and cats, and for treatment of certain internal and external parasites in livestock.

In the Antiviral Research journal article, “The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitro,” the authors found that ivermectin reduced the growth of the SARS CoV 2 virus in cell culture. That novel coronavirus is the causative agent of COVID-19. However be cautious because the research was not conducted in animals and people.

As the public became aware of the research paper there were growing concerns about people wanting ivermectin to treat COVID-19 -- and self-medicating by taking ivermectin products intended for animals.

There is no scientific proof about the safety and efficacy of ivermectin for treating COVID-19. Based on current scientific reports, researchers know ivermectin reduces antiviral activity. But it’s not known if it reduces the severity of the disease or the disease progression in people infected with COVID-19.

When taken for its intended uses, side effects may include skin rash, nausea, vomiting, diarrhea, stomach pain, facial or limb swelling, and neurologic-adverse events such as dizziness, seizures and confusion. Sudden decreases in blood pressure, severe skin rash requiring hospitalization and liver injury have been reported. Laboratory-test abnormalities include decreased white-cell blood count and elevated liver enzymes.

Any use of ivermectin for the prevention or treatment of COVID-19 should be avoided because its benefits and safety for those purposes have not been established. Data from clinical trials are necessary to determine whether ivermectin is safe and effective in treating or preventing COVID-19.

Visit www.fda.gov and search for "ivermectin covid" for more information.

Maria Jose Fuenzalida is a dairy and livestock educator for the University of Wisconsin-Division of Extension in Dane County. Dr. Sandra Stuttgen, veterinarian, is an agriculture educator for UW-Extension in Taylor County.