What's the difference between mirabegron ER versus mirabegron SA? The Rx didn't specify one or the other, but when I transferred it from one pharmacy to another I noticed what I received had changed from ER at the original pharmacy to SA at the new one. (I mentioned it to the prescribing doctor during a visit and he said he thought it only came in extended release and had assumed would be filled as such.) The instructions are the same (1x daily).

How Long Does It Take For Myrbetiq To Work ## HI, Maxine! It should start having some effect within 15 to 20 minutes of taking it, but it may take 4 to 6 weeks to reach its full efficacy level in your body and to see if it will really work for you. Learn more Myrbetiq details here. How long have you been taking it?