PHOENIX - A Moscow mule is a mixed drink consisting of vodka, ginger beer and lime juice that’s normally served in a copper mug.

The Food and Drug Administration states that copper shouldn’t come into contact with foods with a pH lower than 6. That includes vinegar, fruit juice and wine.

Lime juice, a staple of the Moscow mule, typically has a pH between 2 and 2.4, which puts it in the danger zone.

The metal can leak into the food or beverage and cause copper poisoning, which has symptoms include stomach pain, diarrhea, vomiting and jaundice.

Health officials in Iowa and the Iowa Alcoholic Beverages Division just released an advisory bulletin reminding anyone selling and serving alcoholic beverages in copper mugs of the federal guidelines that cups with interior linings of copper and copper alloys may not be used with drinks with a pH lower than 6.

However, copper mugs with interior linings of stainless steel or nickel are safe to use.