Copper mugs are a hot trend at bars serving alcohol. These mugs are very Instagram-worthy and add a certain oomph to the drink. One of the most commonly served drink in these mugs is the Moscow Mule: a refreshing mix of vodka, ginger beer and lime juice. However, according to a report by the Daily Mail, consuming alcohol in these pretty mugs could give you food poisoning if the mug isn't specially made for cocktails.

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Iowa's Alcoholic Beverages Division states that copper and copper alloys are poisonous if consumed. They warn against high consumption of copper as it causes food-borne illnesses. Accidental consumption of copper may occur when copper vessels are used to consume food or drink of a pH level lower than 6, the lower pH causes copper to leak into the substance.

The Food and Drug Administration's Moral Food Code has banned copper and copper alloys from coming into contact with foods that have a pH level lower than 6 because of the risk of poisoning. Many cocktails including Moscow Mule have pH levels well below 6 and this is the reason many US states have issued warning against serving cocktails in copper mugs not specially made for the purpose.

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However, the drink can still be enjoyed in copper mugs that are lined with another metal such as nickel or stainless steel. This way copper does not leak into the substance and there is no risk of food poisoning.

The Alcoholic Beverages Division wrote in its public warning: 'Copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available.'

Thus, you should always check your copper mug for the lining before consuming your food or drink and you will be good to go.