I started taking fluoxetine 10mg last weekend. Apart from the expected dizziness/fuzziness and slight nausea, I had no major issues with it. I woke up around 5am this morning (this is kind of typical for me lately) and felt like my heart was racing/fluttering (this is also not unusual thanks to anxiety). I wear a watch with a wrist-based heart monitor that I use mostly for running, so I clicked over to look at my heart rate, and it showed that my HR had been in the 30s all night. My typical sleeping HR is in the upper 50s to low 60s, possibly dipping into the upper 40s when I am in the middle of training for a half marathon and doing lots of cardio (not the case at the moment).
Here's the thing, though--I'm not sure if my HR monitor was malfunctioning, or if my HR was indeed in the 30s as a side effect of the fluoxetine. According to my watch, my HR dipped from low-60s down to low 30s right around 10:40pm and stayed there until I woke up at 5am. However, I was still awake at 10:40pm--sitting on the couch watching TV. I went to bed around 11:30 and read until about 12:15 when I finally went to sleep. Is it really possible that I had a HR in the 30s while I was awake and didn't feel anything? I wasn't lightheaded or dizzy, and didn't feel unusually fatigued (just the usual end of day tiredness) or out of breath.
I've been checking my HR throughout the day today, and everything seems normal while I'm up and about--ranging from the upper 60s to 80s while sitting at my desk and going up to about 120 when I went for a walk outside. The HR monitor seems to be accurate at the moment, as I've taken my pulse manually and the two numbers are close. Previous days' data look perfectly average for me--it's just last night that I had the super low HR.
I put a call into my psychiatrist this morning to see if I should discontinue the fluoxetine, but have not heard back yet. I did not take my dose this morning. I'm also on tizanidine 2mg a night for migraine prevention, but I've been on that since October so I don't think that could be the culprit (though maybe an interaction with the fluoxetine?).
Has anyone experienced anything like this with fluoxetine? I know bradycardia is listed as a possible side effect, but not sure if it's cause for discontinuing or one of the temporary side effects that clear up after a few weeks. I just don't want to do permanent damage to my heart.
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