Ginormous Flatworm!

I have a nasty chemical that will eradicate almost any flatworm. The only side effect I can think of is whether or not this flatworm secretes toxic chemicals as it is dying? Maybe Cheryl knows...?

Anyways, the chemical is Levamisole HCL. It is a sheep de-wormer and can be found at tractor supply. It's some powerful stuff but is not toxic to anything in the tank unless you way overdose. I have used it in my tank before.
I would recommend direct injection of levamisole with a syringe, that way you know that it's getting enough concentration and dying for sure!