There are many diet drinks on the market that do not contain aspartame, including a specially labeled version of Diet Coke, Diet Rite, Hansen's Natural soda, Pepsi One and Zevia. Most of these products use Splenda, a sugar-derived artificial sweetener, or stevia, a natural sweetener that is up to 300 times sweeter than cane sugar.
Aspartame is a controversial sweetener that is used in many low-calorie or "diet" foods. Many negative side effects have been attributed to aspartame through the years, including memory loss, mood swings, diarrhea, dizziness and migraines. Many diet Coca-Cola products, Diet Pepsi and Diet Dr. Pepper Zero all contain this sweetener.