Really, don't. The alcohol isn't denatured (no firm would ever get a licence to sell a medicinal product, containing methanol, that could be swallowed), it's much worse. Sodium fluoride is as toxic to red blood cells, as sodium cyanide is to all the other cells in your body (and you really need functioning red blood cells). So, a good gutful of Listerine (or equiv mouthwash) can put enough fluoride ions into your body for you to asphyxiate, even though you can fill your lungs with air...
What is the mechanism of RBC toxicity? Does it have anything to do with phosphatase inhibition?