From 2005 to 2007, a Mountain Dew energy drink variant known as Mountain Dew MDX was available, which used an enhanced version of the original Mountain Dew formula to promote athletic activity. The bottles used for this drink were shaped much different than the regular dome-like bottles and had grooves towards the bottom for holding.
The sidekick bottles began appearing in test markets in a small number of states on the east coast. While there is no exact list of these states, they are confirmed to exist in Maryland, Washington D.C., South Carolina, North Carolina, Georgia, and quite possibly in Tennessee and Florida as well.
The sidekick bottles were used for all flavor variants, including those that were only available for a limited time:
- When the FanDEWmonium promotion entered its final phase, Diet Voltage and Diet Supernova both saw shelf releases, and were available in standard and sidekick bottles in the testing states.
- During the Back by Popular DEWmand promotion, Pitch Black and Supernova were available in both standard and sidekick bottles in the testing states. Typhoon also returned for this promotion, but it was only available in 2 liter bottles at WalMart stores.
- In the 2011 Game Fuel Promotion, the original Game Fuel flavor returned, along with a new companion flavor. Both were available in both standard and sidekick bottles in the testing states.
It was hinted by a Dew Labs moderator that the sidekick bottles would be expanding to other areas, stating that it takes time to install the new equipment to shape the bottles. This was backed up by an official Pepsi Distributor website updating their New Products page in January 2012, now including the sidekick bottles and stating that they would be available everywhere in that same month. Recently, there have been reports of sidekick bottles on shelves in the mid United States, indicating that 2 sizes are, in fact, spreading to other areas.
With the relaunching of the Mountain Dew brand in Canada, sidekick bottles are used for all forms of the 591ml bottles, and were used in DEWmocracy Canada as the main form of bottle. The sidekick bottle is currently used for Citrus Charge, Voltage, and Code Red in that country.
In 2015, Sidekick bottles were introduced in Uganda and meant to be released in other countries as well.