These are my thoughts on the topic, but be sure and read Dr. Molly’s professional medical opinion. If you tend to retain a lot of water (as I do,) I think you may find yourself urinating more than usual. I find that I get really bloated during my period and spend more than my usual time in the bathroom for a couple days.
I haven’t run into the issue of peeing more than normal while PMSing. But, unfortunately, I have experienced the luxurious (I say that sarcastically) symptoms of a bladder infection. I’m not sure whether or not your peeing a lot is related to possibly having a bladder infection, but I wanted to throw it out there so that you’re aware and can maybe look out for the symptoms, which include the constant feeling like you’ll pee your pants, a slight burning each time you pee, and the frustrating reality that after stampeding to the bathroom, there’s only a drop of pee that needed to come out. If it doesn’t sound like you have a bladder infection and that having to pee more than usual is actually related to your period, then hopefully Dr. Molly can provide more insight.
As with the above, I also always thought one reason could be my uterus is swolen and so 'pushing' on my bladder, somewhat like a mild version of being pregnant?" - Shadow
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