So it's come to this: A store in Las Vegas will only let customers purchase horse dewormer if they can show a picture of themselves with their horse.

Animal feed store ATV&V Tack and Feed had seen increased demand for the horse dewormer Ivermectin over the last few months, raising suspicions that people aren't using it for its horse-deworming properties. One customer confirmed this to the manager of the store, noting quite casually that he'd been taking the drug despite experiencing alarming side effects.

"I had a gentleman come in, he was an older gentleman, he told me that his wife wanted him to be on the Ivermectin plan. I immediately brought him over here, because at that time I had this sign hung up, and I told him this isn't safe for you to take," manager Shelly Smith told Local 12. "And he says, 'well we've been taking it and my only side effect is I can't see in the morning.' That's a big side effect, so you probably shouldn't take it."

Agreeing with the Food and Drug Administration (FDA) that you should not take horse drugs if you are not a horse, the manager put up a sign making their policy clear, reading "Ivermectin will only be sold to horse owners. *MUST SHOW PIC OF YOU AND YOUR HORSE*" next to a second sign warning that using drugs meant for horses can cause severe injury or death in humans.

Some people online have come up with a few workarounds for the rule, though they may need a little work.

Despite the usual convention that you never buy human medicine from pet stores (for instance, pharmacists would probably not say "you can find the insulin next to the squeaky bone toys") they are not the only animal store to have seen increased demand for the drug. Modern Pet Foods in northwest Harris County, Texas, telling ABC 13 that they usually only sell around 10 of the packets a month, which has increased to around "50 to 100 each".

Ivermectin has been praised by anti-vaxxers as a miracle drug, despite there being no data to support their claims. One meta-analysis which did show positive results for the drug has been redacted at the authors' request following the discovery of fraudulent data in one of the studies. Following the removal of the study containing fraudulent data, the meta-analysis showed no benefit on survival by taking the drug.

The FDA's message on taking horse-dewormers remains clear:

"For one thing, animal drugs are often highly concentrated because they are used for large animals like horses and cows, which can weigh a lot more than we do – a ton or more," the FDA write on their website. "Such high doses can be highly toxic in humans."