After what the CDC cited as a “19-fold rise” in the use of ivermectin, health officials have issued a warning saying that the drug should not be used to treat COVID-19, ABC News reports.

In a lengthy article, the FDA wrote that its job is “to carefully evaluate the scientific data on a drug to be sure that it is both safe and effective for a particular use, and then to decide whether or not to approve it.” It added that “using any treatment for COVID-19 that’s not approved or authorized by the FDA, unless part of a clinical trial, can cause serious harm.”  

The drug is mainly known as a deworming drug, and is often used to treat parasites in farm livestock, such as horses and cows. The increased use of ivermectin has additionally led to an increase in hospitalizations, according to the FDA. The poison control center also added that two-thirds of recent calls were related to the ingestion of ivermectin.

While ivermectin in its early preliminary stages hinted at the possibility that it might help treat or prevent severe disease, a review of the initial studies by the independent National Institutes of Health treatment committee said that the outcomes were unclear and that they couldn’t recommend its use for COVID-19 patients. 

“The high doses that veterinary grade ivermectin is supplied in makes it easy for people to overdose on this medication,” Dr. Joshua Nogar, the medical toxicology fellowship director at Northwell Health and an emergency medicine physician, told ABC News.