Yes, people have in taken stevia for centuries with no known side effects. Individuals who cannot tolerate sugar or other sweeteners usually can tolerate stevia.
Studies recommend that stevia has a regulating effect on the pancreas and could help stabilize blood sugar levels in the body, therefore making it a safe dietary supplement for people with diabetes, hypoglycemia, and candidiasis.

In USA FDA still has not approved Stevia as a sweetener.  However, since the Dietary Supplement Health and Education Act of 1994, they have approved it as a dietary supplement.

Stevia should not be cloudy and it is very rare for this to occur. This usually will occur due to some kind contamination:

• Introduction of another interacting substance
• Bacterial growth due to alcohol evaporation.
  

Simply put, stevia is a remarkable plant (Stevia rebaudiana); many times sweeter than sugar with virtually no calories Stevia rebaudiana is a small plant native to Paraguay and Brazil. It was discovered in 1887 by a South American scientist named Moises Bertoni who learned of the herb from the Guarani Paraguayan Indians who used it to flavor bitter tribal beverages. Two French chemists named Bridel and Lavieille began to unravel the secret of stevia in 1931 with explatory extraction work on Stevia rebaudiana leaves. Their research yielded a pure, white, crystalline compound they named stevioside, which is responsible for stevia's flavorful properties.

Stevia is used for its increasingly researched potential for inhibiting fat absorption and lowering blood pressure. Due to its almost zero calorie nature, Stevia is extremely useful to bodybuilders or obese persons that are attempting to loose body fat.