New Hampshire Gov. Chris Sununu vetoed a bill on Friday that would have permitted pharmacists to dispense ivermectin, a parasite drug, to treat COVID-19 by means of a standing order without a prescription.

Some Americans have been turning to ivermectin to treat the virus, a cheap drug used to kill worms and other parasites in humans and animals. Health experts and medical groups have been pushing to stamp out use of the drug, warning that it can cause harmful side effects and that there’s little evidence it helps.

Sununu said in a news release that New Hampshire currently only has four instances in which pharmacists can dispense medication without a prescription: smoking cessation, contraception, substance use disorder, and treatment for sexual assault.

He said all of them "have gone through rigorous reviews and vetting to ensure they meet all the necessary protocols prior to a medication being dispensed via standing order."

He also said ivermectin remains available for individuals if prescribed by their doctor.

"Patients should always consult their doctor before taking medications so that they are fully aware of treatment options and potential unintended consequences of taking a medication that may limit other treatment options in the future," Sununu said.