Pennies taste metallic, slightly bitter, and faintly sour. The sensation is often compared to the taste of blood, and that’s not a coincidence. The metals in a penny interact with your saliva and tongue in ways that create a surprisingly complex sensory experience, one that goes beyond simple flavor.
Why Pennies Taste Like Blood
The metallic tang you get from a penny is strikingly similar to the taste of blood, and both sensations trace back to the same element: iron. When metals like copper and zinc contact the moist surface of your tongue, they trigger reactions that produce the same compounds found in hemoglobin and myoglobin, the iron-rich proteins in blood and muscle tissue. Research published in Current Nutrition Reports found that iron in the form of heme is likely the main molecule behind the characteristic taste of meat and blood. Your tongue reads the penny’s metals through a very similar channel.
But metals don’t just dissolve on your tongue the way sugar or salt does. Something more interesting happens.
Your Mouth Turns a Penny Into a Battery
Modern pennies, minted after 1982, are 97.5% zinc with a thin 2.5% copper plating. That two-metal structure is key to the taste. When both zinc and copper contact your saliva simultaneously, they create a tiny electrical current, essentially turning your mouth into a weak battery. Researchers measured the voltage produced by a penny’s zinc-copper interface sitting in human saliva and recorded about 550 millivolts, roughly a third of an AAA battery.
This small electrical charge stimulates taste receptors directly, particularly the fungiform papillae concentrated on the front of your tongue. That’s why the taste is strongest on the tip of your tongue and less noticeable further back. Studies in Chemical Senses confirmed that the intensity of metallic taste from coins depends on the voltage generated and is strongest in areas dense with these taste structures. Severing the nerve that serves the front of the tongue (the chorda tympani) nearly eliminates the ability to detect this electrical taste, confirming that the sensation runs through genuine taste pathways, not just touch or pain.
This means the “taste” of a penny is partly chemical (metal ions dissolving into saliva) and partly electrical (a galvanic current zapping your taste buds). The two mechanisms work through different sensory routes. The chemical component involves retronasal smell, meaning some of what you perceive as taste is actually processed through your nose. The electrical component bypasses smell entirely and acts directly on oral taste receptors. Block your nose and you’ll still taste the electric tang, but the fuller metallic flavor dims.
Older Pennies Taste Different
If you’ve ever noticed that an older penny tastes slightly different from a newer one, the composition explains it. Pennies minted before 1982 were 95% copper and 5% zinc. That much copper gives a stronger, warmer metallic flavor, closer to what you’d taste licking a copper pipe. The galvanic effect is also weaker because there’s far less zinc to react with the copper.
Post-1982 pennies, being almost entirely zinc under a paper-thin copper shell, taste sharper and more bitter. Zinc has a harsher metallic quality than copper. If the copper plating is worn or scratched, exposing the zinc core, the taste becomes more intense and more unpleasant. The age, wear, and condition of a penny all shift the flavor profile slightly.
What Else You’re Tasting
A penny that’s been in circulation picks up more than just fingerprints. Coins pass through thousands of hands and sit in pockets, purses, parking lots, and vending machines. Studies examining circulating coins have found a range of contaminants, including intestinal parasites like Giardia. In one study of 180 coins, over 22% were contaminated with detectable pathogens, with coins collected from public restrooms and food vendors showing the highest contamination rates.
The oils, sweat, dirt, and organic residue on a well-traveled penny add a slight musty or dirty undertone to the metallic taste. That “old penny” flavor people describe isn’t just metal. It’s metal plus decades of human contact.
Why Swallowing Pennies Is Dangerous
Tasting a penny briefly is one thing. Swallowing one is another, and the danger comes specifically from zinc. When a modern penny sits in stomach acid, the acid eats through the thin copper coating and begins dissolving the zinc core. This can cause stomach pain, vomiting, and diarrhea as zinc leaches into the digestive system.
A single swallowed penny usually passes without serious harm, though doctors recommend monitoring for symptoms within 24 hours. Coins are the most commonly swallowed foreign object among children, and a penny’s 19-millimeter diameter means it can typically pass through a child’s digestive tract. The real danger comes from coins that get stuck in the esophagus or from swallowing multiple coins. In one extreme case, a man who had swallowed 461 coins (425 of them pennies) required surgery and was diagnosed with severe zinc toxicity. Despite treatment, he died 20 days later.
Even a single penny lodged in the esophagus or stomach for an extended period can cause tissue damage as zinc dissolves. The National Capital Poison Center notes that in severe cases of zinc toxicity, death can occur. This risk applies specifically to post-1982 pennies because of their high zinc content. Older, mostly-copper pennies pose less chemical risk, though they can still cause choking or obstruction.