A report by Northwest Dentistry says sucking on sour candy can be nearly as bad for your teeth as consuming battery acid. Teeth start losing enamel at pH 4, and many sour candies have a pH of 3 or less. Battery acid has a pH of 1.
Several candies have a pH very close to that, including WarHeads Sour Spray (pH 1.6), Wonka Fun Dip Powder (1.8) and Pixy Stix Powder (1.9). Even original Skittles and Brach’s Gummi Bears have a pH of 2.5.