Diet Pepsi was introduced in 1964 as Pepsi-Cola’s first diet cola.
The product began as a low-calorie extension of the Pepsi-Cola brand during a period when diet soft drinks were becoming more popular. It was initially marketed in the United States as a way to enjoy a cola taste with fewer calories than regular Pepsi.
Diet Pepsi followed Patio Diet Cola, a diet beverage associated with Pepsi’s parent company, but it carried the Pepsi name from its introduction. This distinction matters because Patio was an earlier product while Diet Pepsi became the long-running national diet-cola brand.
Diet Pepsi is often confused with Pepsi Zero Sugar, which is a separate product designed to provide a full-cola taste without sugar. Pepsi Zero Sugar was formerly known as Pepsi Max in many markets and was renamed in the United States in 2016.