Symptoms and Consequences
Gladers who go through the Changing are prone to hallucinations and seizures. Their physical attributes often include greenish, prominent veins, a case of hives, and self-inflicted bruises and scratches. A particular attribute of interest is bloodshot eyes.
After the Changing, the person gets back some of the memories that were wiped before they came into the Glade. These memories are often fleeting, as most, such as Gally, only recall bits and pieces of what had transpired in the past. Most of the memories are horrible, causing some people to go insane after the changing, such as Ben who had attempted to murder Thomas while still dealing with the aftermath of the Changing.
Benefits and Uses
In the Maze Runner, Thomas purposefully gets stung by a Griever to go through The Changing, and retrieve memories. Those memories are then used to help the Gladers escape The Maze, but for that to happen he has to take the serum.