The medication stigma is based on basically magic thinking: That medicine is alien, external, unnatural while the human body is pure and natural. Therefore any difference between medicated and unmedicated is artificial and caused by the medicine.
No, the body is fucking dropping terror chemicals in my bloodstream. It is changing my personality from easygoing and outgoing to snippy and reclusive. The body is malfunctioning and changing my personality for the worse.
The medicine is reducing the amount and effectiveness of the body's excess of terror chemicals. It restores normality.