Too much magnesium?

I take a daily multi vitamin tablet which contains 100mg of magnesium and eat a couple of bananas a day, while I also eat a lot of oily fish and tend to have a small portion of rocket with many of my meals.

About six weeks ago I read a thread on here about the beneficial effects of magnesium and decided to up my intake by taking a 500mg Magnesium Citrate tablet every day (they contained 80 mg of elemental magnesium).

After around a fortnight I entered a three week period where I became far more prone to ectopic and double and triple beats than I am normally. I've gone into full details of what happened in another thread, so all I'll say here is that the unusual heartbeats followed a regular pattern whereby they'd be absent during the nights and then last for much of the day after starting shortly after I'd had the magnesium tablet with my breakfast, before fading in the four or five hours before I went to bed.

About halfway through this three week period, I decided to stop taking the magnesium tablet and, around ten days ago, the unusual heartbeats stopped and have not returned.

I realise I should have run it by someone at my health centre before starting to take the magnesium tablets and will do so when I have my INR on Monday.

I've done some research and found that too much magnesium can cause heart palpitations, but the impression I got was that the quantities involved would have to be greater than I was taking, yet, to this non expert at least, the evidence points to the magnesium being the cause of them.

19 Replies

  • I can't take Magnesium either but because of another condition. I think we all need to be quite careful taking supplements and also remember that ANY substance we ingest which has the capacity to treat a condition also has the capacity to cause the symptoms you are trying to treat, it is SO individual one cannot generalize.

    I haven't read your previous post but would be interested in the replies.

    Best wishes and good post.

  • Morning CDreamer and thank you - the other message I posted is in the "Am I on verge of AF" thread.

  • I always caution people to discuss any supplement with their health care providers before taking. There are many magnesium disciples on here who would have us all on the stuff but NOT always appropriate.

  • I imagine you are describing bigeminy or trigeminy there.

    I have had periods of these before too. One lasted around 3 weeks, several years ago now and it stopped the day before I was due a 24 hr monitor! I think it's common for those to come and go in periods of that length so chances are it would have stopped anyway. Mine at the time did not go away at night, so perhaps the magnesium helped you there?

    I have taken magnesium supplements(a heavier dose than you) for 3 years and am convinced they help me.

    I imagine you will never know if your spell of ectopics were due to the magnesium or possibly the magnesium prevented them from becoming AF. ? You are not going to know.

    Personally I doubt if 600 mg of magnesium would take you into a 'too much' category.

    Were you in good health at the time? Unwell at all?

    I say that because shortly after I began my bigeminy/trigeminy spell a few years ago, I developed a cold/flu like virus and I think it was the constant coughing phase which abated the palpitations.

    You will only know by trial and error with the magnesium but I think you may have already made your decision.


  • Thank you Pat. I've decided to make further enquiries and would be open to taking the tablets again depending on the answers I get. I'm interested by your suggestion that, far from causing the ectopic beats, the extra magnesium may have prevented the sort of three week AF outbreak which I described in the other message I've referred to in this thread. My instinct is to say that because the unusual heartbeats started after taking my daily tablet that this was not the case, but,as they have often been in my AF journey, those instincts and beliefs could be wrong.

    As for my health at the time, it was much as it normally is - the usual aches and pains you get in the autumn of your life (!) and the slightly zonked out feeling I put down to the Bisoprolol, but nothing else.

  • Hi there

    Can I ask you if it's magnesium taurate that's the best for AF?

    Many thanks

  • Personally I take taurine as a separate supplement and take magnesium as magnesium glycinate and magnesium citrate.

    Don't but magnesium oxide though as that is apparently the least effective.


  • Thank you Pat, most appreciated.

    Best regards

  • Sorry Pat me again! Can you tell me where you buy your Magnesium? I've been looking on various websites but I'm a bit concerned I'm getting the correct one.

    Many thanks


  • I buy all of mine from Amazon. That's purely because I'm a Prime member and get next day delivery, not because it's necessarily the best place to buy them.

    Here's are 2 I have at the moment;


  • Thank you Pat, I've ordered the mag citrate and the mag glycinate from Amazon.

    I'm very grateful for your advice.

    Best wishes, hope you have a good day.


  • best if you only experiment with one variable at a time and keep notes. Good luck finding the best program for you personally!

  • "Doses (of magnesium) less than 350 mg per day are safe for most adults. When taken in very large amounts, 600 mg and upwards, magnesium is POSSIBLY UNSAFE. Large doses might cause too much magnesium to build up in the body, causing serious side effects including an irregular heartbeat, low blood pressure, confusion, slowed breathing, coma, and death."

    Straight from the leading US medical website How authoritative this is, I can't say, but it should at least prompt caution.

  • I tried many different vitamins including magnesium, coQ10, fish oils etc. and avoided certain foods that I thought caused or triggered Af

    I can honestly say that none of them made any difference at all, if only it were that simple !

    my Af stopped after I had an abalation , no medicine, vitamin supplement or change of diet or lifestyle achieved that.

  • I guess like drugs you have to live and learn with supplements.

    I would start on a lower dose of Mg Citrate say 125mgs per day or you might want to try what my Naturopath put me on which worked well Nutri Ultra Muscleze; google it to see all the beneficial constituents as it is a compound. I consider it my best supplement and wouldn't stop it.

    Good Luck.

  • Just to say that I planned to give the whole story of what happened to me to the nurse who did my INR yesterday, but I had only managed to tell her the total amount of Magnesium I was taking when I was on the Magnesium Citrate supplement and she said "that sounds like you're taking too much of it to me".

    I went on to tell her about the increased number of unusual heartbeats I was getting and how they had stopped once I ceased taking the supplement and she said it sounded to her as if I was getting enough Magnesium in my diet without the need for any supplements (I also take a multi vitamin tablet daily which includes 100 mg of magnesium).

    She did say that she would check with one of the GPs about here suspicions and came back to tell me that they had agreed with her.

    So, with my heart having now been behaving itself for the past fortnight, I'll not be returning to the Magnesium Citrate for the foreseeable future, but I think I'll run it by the EP when I see him in January.

  • Sounds like you have tested that one successfully for you.

    It's a bit of a guess but I suspect your calcium/dairy e.g. milk, yoghurt, cheese is quite low and therefore the Mg is not getting partially blocked. I read these two compete against each other for absorption, one blocking the other and vica versa.

  • I have one of those small pots of Pro Activ yogurt every day and have a bowl of porridge (made with skimmed milk) most mornings, but, that apart, I don't eat a great deal of dairy produce, so you might be right.

  • Conversely, I love real quality dairy, raw milk, organic yoghurt and cheese, kefir etc and I struggle with supplements to get my Mg into the normal range, using the Red Cell test not the normal GP test which almost always shows OK.

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