They do appear to work as of 7438, but with Tainted Tornadoes and Mutagens, and probably with Serums as well, there is still a possibility that you can consume one and not get a new mutation; that’s normal. Tainted Tornadoes also give you a very heavy depressant debuff, at about Depressants [60] per drink. If you drink 2-3 of them simultaneously your character will pass out. Even if you’re somewhere that no zed can happen upon your unconscious form and nom on you at a leisurely pace, this can and will lead to death because you also gain hunger and thirst at a very fast pace in this state.
If you’re going to mutate it is highly recommended to take Robust Genetics if you haven’t already. Mutagens have a chance (I believe it’s roughly 33%) to give you a negative mutation and nothing else and, the way I understand it, Robust Genetics changes that to an equal chance to give a positive mutation and nothing else.