Whatever is in acne medication is a bleach on fabrics. People find stains on towels and the necks of dark shirts as well. You cannot remove this stain from the rug, as it is not actually a stain. The medication has removed the color from the rug. You must do what others have suggested -- either try to camouflage the spot with colored markers, replace that piece of rug with another piece cut from inside the closet or under the sofa or from scraps you might have, or put a throw rug or a piece of furniture on top of it.
I have a gray carpet with black design in it. I spilled a little bleach on it, so I had a black sharpie and colored it black. Now you can't even tell where the stain was. These Sharpies come in different colors. Good Luck!
The spot is probably bleached & hence the colored spot. I would suggest trying to fill in the color with permanent markers the same color as the rug. Or cut a piece of rug (if it's wall to wall) & try to patch it, or put another small rug on top of it.
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