There are no common side effects of Prevagen, as the body tolerates it well, according to Prevagen. In an October 2012 warning letter to the product manufacturer, the U.S. Food and Drug Administration stated product users had reported experiencing adverse events including seizures and strokes.
Prevagen's main ingredient is apoaequorin, which scientists have agreed is safe enough to use in food. Clinical studies have shown apoaequorin helps improve memory, according to Prevagen. The October 2012 FDA warning letter to Prevagen's manufacturer Quincy Bioscience Manufacturing states the company did not report adverse events such as fainting, increased multiple sclerosis symptoms, irregular heartbeat, chest pain and vertigo, according to the FDA.