It's like eating a pill, it depends on what point you take it out of the system, and you'd be working fast considering what flowers are made of. If you got it out of the system within let's say 15 seconds of it being swallowed, you would be fine, but any more, the effects would become more and more prominent.
This, kinda also dephends on how the red flowers work. getting it out immediately could likely leave a mimiga mostly fine, if not completely unaffected
The trouble in this matter though is actually getting a mimiga to throw out the flowers after eating them.
Even if we consider the time from swallowing to the flowers taking their possible effect to be around 15 seconds, that can still prove to be a very short time to get someone to throw up the flowers. Even when King knew what to do it could've already been too late to help Toroko the moment he gets to her.
And even if it's possible the effects can (mostly) wear off even after that, you'd first have to devise a way to stop a rabid mimiga from rampaging without killing them, and when Toroko shows the ability to throw large stone blocks, it is not an easy task at all.
And that's assuming the rabid mimiga in question has eaten the flower recently, if you take too long there isn't really much to regurgitate, and at that point it's most likely too much in their system. And medicine or other such things most likely are not known about.
However, the best way to stop rabid mimiga mutation is not to try and get it out of the system or cure it, but to prevent mimigas from eating the red flowers to begin with!