The copper cup your Moscow mule comes in is shiny, sleek and oh-so-Instagram-able, but it could be poisoning you.

Iowa health officials recently cautioned bars against using pure copper mugs for the ginger beer, vodka and lime cocktail, since the acid in lime can cause the copper to leach into the drink and potentially cause gastrointestinal problems.

And similar products making the rounds in trendy yoga studios and on wellness blogs may pose the same risk, despite their many dubious health claims.

Ayurvedic “drinking vessels” made of copper are said to re-oxygenate blood, reduce cancer risks and prevent aging —claims that are scientifically unproven, according to Dr. Terry Gordon, an environmental medicine professor at the NYU School of Medicine.

That hasn’t stopped Amazon reviewers from frequently raving about how pretty the bottles look. The supposed benefits of these containers date back to historical Indian medicine.

And despite the fact that copper does have antimicrobial properties (potentially killing some bacteria), using these bottles could potentially do more harm than good, says Gordon.

“I don’t see anything in the medical literature about [these benefits],” he says. “In water pipes or soil, yes, but there’s just no data on water bottles or copper pots.”

The Centers for Disease Control and Prevention warns that drinking water that contains higher-than-normal levels of copper could cause nausea, vomiting and diarrhea, while very high levels can lead to death.

And while drinking water out of copper water bottles may be OK, leaving it to sit overnight — as some water bottle sellers recommend — is not advisable, he says.

“Leaving it in overnight would increase the leaching of copper into the water,” Gordon says. “The amount may or may not be dangerous — it depends on how freely available the copper is, the pH of the liquid and the sensitivity of the individual to copper.”

Whatever you do, don’t put acidic juices, such as orange or grape juice, in the bottle. Those make the leaching even worse, he says.

“It’s a personal choice, but why do it if it could cause gastrointestinal problems?”