I've been taking it since Nov. 2018 for severe POTS
I now take 3 doses, 60 mg each, 5 hours apart (8 am, 1 pm, 6 pm)
Did not have any side effects (have had many bad med. reactions in past to other meds.)
Helps POTS somewhat, but didn't touch ME/CFS, actually, made it worse for a time (and this was bad since mostly bedbound to start with

)
I agree with
@Mel9...be very careful with pacing on this med. it easy to do too much if it helps you, but you will pay for it heavily with PEM!
Am still learning what "signals" to pay attention to now. It has been difficult.
But, as an example, I can now load the dishwasher (on days I am well enough) standing part of the time and sitting on a stool all in one go. Before this med, it would take me multiple attempts throughout the day (because POTS symptoms so severe)...like rinse 4-5 dishes, sitting on stool, lay down for 2-3 hours in bed, go back and rinse a few more. Usually would take a coupe of days to fill up dishwasher, now it takes about 10 minutes in one go! For me, that is HUGE!