A lone can of Mountain Dew (labeled Mtn Dew on many shelves) has a way of outliving everyone’s memory of buying it. It turns up at the back of a pantry shelf, under a car seat, or at the bottom of a cooler from a party two summers ago. The date is faded, the can is warm, and the only question is whether it’s still worth opening. Often it is, as long as the container is intact. The caveats are mostly about flavor.
Does Mountain Dew go bad?
The short answer: Not like milk, deli meat, or leftovers. A sealed, undamaged can or bottle of Mountain Dew generally doesn’t become unsafe just because the printed date has passed, since USDA treats that date on shelf-stable food as a quality marker. The drink is acidic and preserved, which makes it a poor place for bacteria to grow, so the usual changes are lost fizz and a duller citrus flavor. Damaged packaging or long heat exposure changes the picture, and Diet Dew’s aspartame can fade in heat.
For a complete pantry storage reference, see our Food Storage Guide.
Does Mountain Dew Go Bad: At a Glance
Sealed can or bottle past the date
Per USDA, should still be safe if handled properly until spoilage is evident; fizz and flavor fade
Diet Mountain Dew and Zero Sugar
Same safety picture, but aspartame can fade faster in heat
Opened, refrigerated, cap on
Best fizz within a day or two; discard if left out for a long time
Storage
Cool, away from temperature extremes; USDA says below 85°F is best for shelf-stable foods
Bulging, leaking, or heavily rusted container
Discard without opening, whatever the date says
Caffeine (12 fl oz)
54 mg in Mountain Dew and Diet Mountain Dew, per PepsiCo
Key Takeaways
Mountain Dew’s acid is citric acid, and its label lists preservatives, so a sealed container is a poor environment for bacterial growth.
The date stamped on a can is the maker’s estimate of peak flavor, and USDA says dates aren’t an indicator of a product’s safety.
Heat is the storage condition to avoid. For shelf-stable food in general, USDA says below 85°F is best.
An opened bottle or can loses fizz first, and acidity isn’t a guarantee of safety once the drink has been open for a long time.
Cans from before 2020 may list brominated vegetable oil (BVO), which FDA has since banned from food. Current Mountain Dew does not.
A 12 fl oz can has 54 mg of caffeine, more than the 34 mg Coca-Cola lists for a Coke.
Why Mountain Dew Doesn’t Spoil Like Most Foods
Perishable food goes bad because bacteria and molds find moisture, nutrients, and a comfortable pH. Mountain Dew has plenty of sugar, but it is also an acidic drink. A University of Florida extension publication on processing acidified and low-acid foods notes that C. botulinum spores won’t germinate and grow in foods with a pH of 4.6 or below. A 2016 survey of 379 U.S. beverages in the Journal of the American Dental Association found that 93 percent had a pH below 4.0, well under that line. The survey wasn’t specific to De
