In one of my college marketing classes we studied Tylenol’s damage control efforts. It was masterfully done.
If I remember, they took all of their products off the shelves across the country. They stopped selling the openable capsules and began selling the solid pill version. Then they started doing the sealing of the caps. I also remember a bunch of "copycat" tamperings that then occured. One guy had his eyedrops replaced with some kind of glue or acid.