The most caffeinated mainstream soda
A 12 fl oz can of Mountain Dew carries 54 mg of caffeine, by PepsiCo’s own product facts. That is more than any of the major colas: Coca-Cola has 34 mg, Pepsi 38 mg and Diet Coke 46 mg. Diet Mountain Dew matches the original at 54 mg, so switching to diet removes the sugar but not the caffeine.
It is still well below coffee and most energy drinks. A can is a little over half an 8 oz cup of drip coffee at USDA’s reference strength (95 mg), about two thirds of a standard 8.4 oz Red Bull (80 mg), and roughly a quarter of a can of Celsius (200 mg).
Kickstart reads lower than it is
Mtn Dew Kickstart, sold as a morning drink, carries 92 mg in its 16 oz can. PepsiCo’s label splits that into two 8 oz servings of 46 mg each, so the per-serving line looks lower than the can most people will actually drink. The figure here is for Orange Citrus; check the label for other flavours.
PepsiCo lists caffeine on its product pages for each container size, so for a bottle or a fountain cup, check the figure for that size rather than scaling up from the can. For no caffeine at all, PepsiCo sells a caffeine-free Diet Mountain Dew.
Teenagers
Mountain Dew’s caffeine is the reason it deserves a second look for teenagers. The calculator on this site sets a teenager’s limit at 2.5 mg per kg of body weight at its default sensitivity: 125 mg for a 50 kg teen. Two cans, 108 mg, fit under that; a can plus a 16 oz Kickstart, 146 mg, does not.
The FDA notes that too much caffeine in children and teens can cause increased heart rate, heart palpitations, high blood pressure, anxiety and sleep problems. For adults, seven cans (378 mg) stay under the 400 mg a day the FDA cites for healthy adults, and the eighth goes over.