Oh! So it might be just the citrate form. I take magnesium in summertime to prevent cramps, but noticing the bowel stimulation, I sometimes take it for that too when needed.
Incidentally, citrate tastes like sh**. Are other salts better?
If you can find an honest supplier, Magnesium Bisglycinate (commonly called Magnesium Glycinate) is the most absorbable form and doesn't give you the shits.
A few years back I was having issues with "extra" beats and it felt as though my heart was stopping - a very unnerving feeling. Long story short, after several months of specialist care and testing, I still had it continuously every.damn.day. and then one day, my youngest was giving me a hard time about going to bed so I picked her up and ran up the stairs with her... my calf muscles felt as though they would cramp every step and the next morning, my back was screwed. Best thing that ever happened to me! Honestly. Ordinarily, I would have just toughed it out until it subsided but we were going away for our long-awaited summer vacation and I wanted to enjoy it so I crossed my fingers and I called the chiropractor. This was mid July... (oh, the heart skipping had been going on since the previous September) On the very first visit, she asked me some questions - do you ever get cramping in your legs? Oh yeah all the time, sometimes it wakes me in the middle of the night. I just though it was a symptom of shift work. She recommended a Magnesium supplement and said it might help with my back... they just happened to have a bottle of it too at only $32 for 60 capsules! "Oh yeah", I thought, "here we go with the add-ons... as if you aren't making enough money off me already." Then something wonderful happened - on day two, I noticed my heart was normal and again on day three... she fixed my back within 4 days, my heart issue as well and as an added bonus, I rarely have a slight muscle cramp and I haven't been awakened with a cramp in the middle of the night since either. I haven't felt an extra beat since and I still take one 200mg capsule every day.
Magnesium Bisglycinate.
You really have to watch though because the supplement manufacturers are held to different labelling standards somehow. Even though it says "Magnesium Bisglycinate" or "Magnesium Glycinate" and 200mg on the front, if you look at the ingredient list, it may contain magnesium citrate, oxide or stearate (used to prevent clumping and does not provide any useable magnesium) and they don't print the ratios.
edit: I looked back on the blood work they did when the heart skipping was happening and my magnesium appeared in the "normal" range but to the low side. It wasn't obvious I guess.