Washington, Aug 22 (IANS): A controversial anti-parasitic drug commonly used for livestock -- ivermectin -- but touted as a potential Covid-19 treatment, should not be taken to treat or prevent Covid-19, the US Food and Drug Administration has said here.

The US Food and Drug Administration (FDA) had, in April last year, warned against the use of ivermectin, due to the lack of supporting scientific evidence.

Ivermectin is not an anti-viral (a drug for treating viruses), but has been approved at very specific doses for some parasitic infections like intestinal strongyloidiasis and onchocerciasis, head lice, or skin conditions like rosacea.

"You are not a horse. You are not a cow. Seriously, y'all. Stop it," the FDA said in a tweet on Saturday.

The new warning came a day after the Mississippi State Department of Health issued a similar statement in response to reports that an increasing number of people in Mississippi were using the drug to prevent a Covid infection, the New York Times reported.

"At least 70 per cent of the recent calls have been related to ingestion of livestock or animal formulations of ivermectin purchased at livestock supply centers," the Department said in a statement.

"Animal drugs are highly concentrated for large animals and can be highly toxic in humans. Some of the symptoms associated with ivermectin toxicity include rash, nausea, vomiting, abdominal pain, neurologic disorders, and potentially severe hepatitis requiring hospitalisation," it added.

In March, the World Health Organisation had also recommended against the use of ivermectin in treating Covid patients. The WHO said there was a "very low certainty of evidence" on ivermectin's effects on mortality, hospital admission and getting rid of the virus from the body.

"Safety and efficacy are important when using any drug for a new indication. WHO recommends against the use of ivermectin for #Covid19 except within clinical trials," Soumya Swaminathan, the global health body's chief scientist, said in a tweet.

Covid-19 treatment guidelines issued by the National Institutes of Health (NIH) also states that "there is insufficient evidence for the Covid-19 Treatment Guidelines Panel (the Panel) to recommend either for or against the use of ivermectin for the treatment of Covid-19."

However, ivermectin has been taken up by doctors and by individuals self-medicating in countries, including Brazil, Bolivia, Peru and South Africa.

The FDA said that it has not reviewed data to support use of ivermectin in Covid-19 patients to treat or to prevent Covid-19. However, some initial research is underway.

But, "taking a drug for an unapproved use can be very dangerous. This is true of ivermectin, too.

"There's a lot of misinformation around, and you may have heard that it's okay to take large doses of ivermectin. That is wrong," the FDA said.