Tracey, I take regular allegra.    I can see that the 24hr might not be as effective as the 12 hr form because by the time you get to the 2nd half of it´s effectiveness it may not provide for you the continuity you need.   However, I´m no doctor and don´t know anything about that medicine in that form.   The 24hr sounds good, and I know I prefer taking antibiotics in the 1 pill form just because I get awfully blonde about the hours and such, but meds for all of us are really so controversial!   I`ve heard some patients say, regarding antibiotics, that they would never take the 1 pill only form due to the fact that if you are going to react, it´s a lot more "potent", and yet, I don´t know about that, it doesn´t seem to make a lot of sense to me because whether it´s in the 1pill form or that of 3 a day, if you react, you react regardless of the dosage.  

So, for these things I personally really don´t trust what other patients have to say.   I´ve found out with things like contrast and medical procedures what may make one patient not react will end up putting me into outer space and yet when it comes to meds I tolerate what others would come close to with a 20 foot pole!   And even the doctors aren´t always sure.   But the word of a masto specialist goes a long distance with me, so if you´re not sure about all of this, if you have a masto specialist, then ask them.  If you don´t, then you might want to try writing to an expert and asking them instead.

I hope this helps!

Lisa