Is Drinking Out of Copper Cups Bad for You?

December 23, 2025 •

4 min read

According to the National Institutes of Health, copper is an essential mineral for the human body, but excessive intake can lead to health problems. This is why properly understanding the safety risks is crucial before deciding if drinking out of copper cups is bad for you.

Quick Summary

This article explores the health risks and benefits of drinking from copper cups, detailing the factors influencing copper leaching, signs of toxicity, and proper usage to ensure safety, particularly for acidic beverages.

Key Points

Lined is Safe for Acidic Drinks: Modern copper mugs used for cocktails are typically lined with stainless steel or nickel, which prevents dangerous copper leaching from acidic ingredients like lime juice.
Unlined is for Water Only: Pure, unlined copper cups should only be used with plain water, ideally at room temperature, to avoid significant copper leaching.
Avoid Acid and Heat: Never put hot or acidic beverages, such as coffee, tea, or soda, into an unlined copper vessel, as this drastically accelerates the release of copper ions.
Watch for Overconsumption: Excessive intake of copper-infused water can lead to copper toxicity, with symptoms ranging from nausea to liver damage. Drink in moderation.
Follow FDA Guidelines: The FDA prohibits unlined copper from direct contact with food or drinks with a pH below 6.0, a guideline adopted by many states.
Clean Regularly: Proper cleaning with natural agents like lemon and salt prevents the buildup of copper oxide, which is also a concern for contamination.

The Truth Behind Copper Drinkware

For centuries, cultures around the world, particularly in Ayurvedic tradition, have praised the health benefits of storing water in copper vessels. The practice, known as tamra jal, is believed to purify water and offer antimicrobial properties. However, the modern resurgence of copper drinkware, such as Moscow Mule mugs, has led to public health advisories and growing confusion about whether these vessels are truly safe. The key to understanding the risks lies in differentiating between proper use and dangerous practices, particularly concerning the type of liquid and the cup's construction.

The Science of Copper Leaching

Copper is a reactive metal, and its ions can be transferred into liquids upon contact, a process that is influenced by several factors. For plain water, especially when stored at room temperature for several hours, this leaching is minimal and generally considered safe for healthy adults. This is the basis for the traditional Ayurvedic practice of storing water overnight. However, the presence of certain substances can accelerate this process significantly:

Acidity: Highly acidic beverages, such as fruit juices, soda, and cocktails with citrus (like a Moscow Mule), will cause copper to leach at a much faster and more dangerous rate.
Heat: Hot liquids, including coffee, tea, and hot water, also increase the rate of copper leaching, and should be avoided in unlined copper cups.
Contact Time: The longer a liquid sits in an unlined copper vessel, the more copper ions can be absorbed. This is why immediate consumption is always recommended for acidic drinks.

Lined vs. Unlined Copper Cups

Not all copper cups are created equal. Many modern mugs are actually lined with a non-reactive, food-safe metal to prevent copper from entering the drink.

Comparison of Lined and Unlined Copper Drinkware


Feature	Lined Copper Cups (e.g., Stainless Steel or Nickel)	Unlined Pure Copper Cups
Best For	Acidic and hot beverages, cocktails like Moscow Mules	Plain, room-temperature water stored overnight
Safety	Significantly reduces risk of excessive copper leaching	Moderate risk with improper use (acidic/hot liquids, long storage)
Copper Exposure	Minimal to none, as liquid doesn't contact copper	Small, controlled amount when used correctly; excessive when misused
Maintenance	Easier to clean, less prone to tarnish on the interior	Requires careful cleaning with natural agents (lemon, salt) to remove tarnish
Antimicrobial Benefit	Does not offer antimicrobial properties to the liquid	Imparts mild antimicrobial effect to plain water over time

The Dangers of Excessive Copper Intake

While the human body needs copper, it also has a system for maintaining balance and excreting excess amounts. Problems arise when this system is overloaded, leading to a condition known as copper toxicity. Acute copper poisoning can occur from consuming high levels of copper and may cause severe gastrointestinal issues. Chronic exposure from long-term, improper use can lead to more serious conditions.

Symptoms of Acute Copper Poisoning:
- Nausea and vomiting
- Diarrhea
- Stomach cramps and abdominal pain
- Metallic taste in mouth
Symptoms of Chronic Copper Toxicity:
- Liver and kidney damage
- Neurological disorders
- Depression and anxiety

These severe health risks are why health officials, like those in Iowa citing the FDA's food code, have issued warnings against serving acidic cocktails in unlined copper mugs.

How to Use Copper Cups Safely

To enjoy the potential benefits of copper-infused water while avoiding the dangers, follow these guidelines:

Understand your cup's construction: Check if your copper mug is lined. If it is, you can use it for various cold and hot beverages. If it's pure, unlined copper, reserve it for plain, room-temperature water only.
Stick to plain water: Never put acidic drinks (lemon juice, soda, vinegar, etc.), milk, or hot liquids in an unlined copper cup.
Moderate overnight storage: If following the tamra jal practice, limit water storage to 6-8 hours overnight. Do not leave water in the cup for extended periods.
Practice moderation: Even with proper use, excessive consumption of copper-infused water is not recommended. Many experts suggest limiting intake to one or two glasses per day.
Clean your cup regularly: Use natural cleaning agents like a mixture of lemon juice and salt to remove tarnish and prevent the buildup of copper oxide. Avoid abrasive scrubbers and harsh chemicals.
Recognize the signs: If you experience any symptoms of copper toxicity after using a copper cup, stop immediately and consult a healthcare professional.

Conclusion

For most healthy adults, drinking out of copper cups is not inherently bad for you, provided you use them correctly and in moderation. The primary risk comes from a lack of awareness regarding the type of beverage and the cup's lining. Unlined copper cups are best reserved for plain water, with careful attention to storage time and temperature. For serving acidic cocktails or hot drinks, a lined mug is the only safe option. By understanding these key distinctions, you can safely enjoy your copper drinkware and avoid the risks of excessive copper exposure. For further information on recommended daily allowances of copper, consult the Office of Dietary Supplements at the National Institutes of Health.

Frequently Asked Questions

You can get copper poisoning from a Moscow Mule if it is served in an unlined copper mug. The lime juice and ginger beer are acidic and cause excessive copper to leach into the drink. However, most commercial Moscow Mule mugs are lined with stainless steel or nickel to prevent this.

Yes, it is generally safe to drink plain, room-temperature water from a clean, unlined copper cup. Water can be stored overnight for a mild infusion of copper ions, but you should avoid consuming this water excessively or keeping it stored for very long periods.

A quick visual check can often reveal if a cup is lined. Look inside for a silvery, metallic interior that is different in color and texture from the copper exterior. If the cup's interior looks identical to the exterior, it is likely unlined pure copper.

Symptoms of copper toxicity can range from mild to severe. Initial signs often include nausea, vomiting, stomach cramps, and a metallic taste in the mouth. Chronic or severe exposure can lead to more serious issues like liver damage, kidney problems, and neurological effects.

You should not put any acidic or hot beverages in an unlined copper cup. This includes fruit juices, soda, coffee, tea, milk, and alcohol. These liquids can react with the copper and cause unsafe amounts to leach into the drink.

It is best to clean your copper cup regularly, at least once a week, to prevent tarnish and bacterial buildup. Tarnish, while not immediately dangerous, can affect taste and harbor impurities. A mixture of lemon and salt is a recommended natural cleaning method.

In small, controlled amounts, proponents of Ayurveda suggest benefits such as antimicrobial properties for water purification. Some studies also show copper has antioxidant effects. However, excessive intake can be harmful, and most dietary copper needs are met through food.