While magnesium is generally safe, one of the most common side-effects of taking a magnesium supplement is diarrhea (and sometimes explosive diarrhea!).
Why can magnesium cause diarrhea? It can happen for a number of reasons, such as a poor quality supplement or taking way too much.
Fortunately there are ways to prevent this uncomfortable problem from happening.
The content provided here is for informational purposes only and should not be used in place of the advice of a healthcare professional. While my wife and I have been taking magnesium supplements every day for years, I can't say how they might affect you. Always consult a doctor if you have health concerns: don't try to self-diagnose!
Why Does Magnesium Cause Diarrhea?
Magnesium is a mineral, and when taken as a supplement one of its properties is that it tends to attract water.
When unabsorbed magnesium reaches the intestine or colon it can attract water from nearby tissue through osmosis. This can stimulate the bowels and give you the urge to go.
If too much unabsorbed magnesium reaches the intestines then you can end up with diarrhea and cramping.
Not everyone who takes a magnesium supplement gets diarrhea though.
How To Prevent Diarrhea When Taking Magnesium
As I mentioned, diarrhea is the result of unabsorbed magnesium reaching your intestines.
Ideally you want all of the magnesium you are taking to be absorbed by your body rather than leaving again through diarrhea.
So in order to prevent diarrhea you need to:
- take only enough magnesium to satisfy the needs of your body
- absorb as much of the magnesium you take as possible
If you can find a type of magnesium that your body absorbs well and then take just enough to make your body happy then you should be able to avoid diarrhea entirely.
How Much Magnesium Do I Need?
The Recommended Dietary Allowance (RDA) for magnesium is roughly 300-400mg per day for the average adult, though it varies based on age and gender.
While many foods are enriched with calcium there are few that have added magnesium. Also, the common farming practice of overusing soil can reduce the magnesium content of our food over time. This means it can be tough to get enough magnesium from food alone.
The key is to add enough magnesium through supplementation to get you to the 300-400mg range based on the foods you tend to eat. If you are getting enough through food alone then are doing well!
You can click here to see some foods high in magnesium.
Based on these numbers you should be able to get a rough estimate of how much magnesium you are getting from food each day. From there you can try supplementing a small amount of magnesium and work your way up.
How Do I Increase Magnesium Absorption?
So how do you improve absorption?
First, don’t consume all of your magnesium in one sitting. Instead take supplements in smaller doses over the course of the day.
Next you can try taking magnesium on an empty stomach in order to prevent the fiber in food from binding up the mineral and preventing absorption into the body.
Lastly, take a better quality magnesium supplement. There are a lot of different types of supplements out there and they vary a great deal in their quality and absorption properties.
Magnesium Oxide in particular is very common yet I found it to be the worst when it comes to diarrhea.
For me, Magnesium Glycinate worked wonders, letting me take the magnesium I needed while not giving me diarrhea.
Click here to see the magnesium supplement that stopped my diarrhea on Amazon
Your Turn: Does Magnesium Cause Diarrhea For You?
If you have experience with magnesium making you go, and especially if you have a found a way around it, please let us know in the comments below!
As always, you are strongly encouraged to consult with your physician or other qualified medical professional to help determine your own optimal level of magnesium, and to see whether magnesium supplementation is right for you.
Thank you for posting this feature!!! Just recently started on a new drug, B-12 and Magnesium. Goodness, I’ve had terrible diarrhea for 1.5 wks and thought it was the drug or an ingredient. It may well be…but been taking 1000 mg of mag 2x per day…no wonder I have diarrhea!!
Am stopping it for a few days to be sure.
Bisglycino-Mg by Vita Aid was given to me by my naturopath and I find it to be the best out of the ones I have tried so far for anyone looking for a good quality magnesium. No diarrhea but an increase in stools and urgency. I eat two before bed but talk to your doctor about what the right dose would be for you and your body but its actually helped my TMJ – Jaw clenching and as well anxiety but I also take ashwaganda which has been helping also.
I’ve starting taking “Calm Powder” from natural vitality and it helps me get to sleep and relaxes me, but the diarrhea I am beginning to have is horrible. It makes me sad because I like it other than the diarrhea. A 2 teaspoon serving has 325 mg of magnesium.
I heard that starting at 1/2 teaspoon and working up would help with the diarrhea. I haven’t tried it yet as I haven’t got the product yet but that’s what I intend to do.
Yes I’ve been taking calm for 2 weeks and the diarrhea is unreal. I go about 6 -7 times a day and it’s really explosive and watery. I like how it makes me feel but I think I need to bring the amount way down or either try taking with calcium for better absorbing . Hope you feel better.
I take 800 mg of magnesium Oxide every night with calcium, D3, and 10mg melatonin. My bowels are just right and I fall asleep right away. My only problem I have is waking up early. I can live with that. Constipation I cannot live with.
i took 500 mg of magnesium oxide for constipation once a day at night and it made me regular. i loved it. the brand was Vitacost and its not expensive but only available online. i recently tried a different brand because i didnt want to order online and it was horrible! i got bad diarrhea so i learned that brands matter.
Paula Smith says
Yes, it does. I take 1000 as directed by my Neurologist for help with migraines. It does help with the migraines. I also have Sjogren’s that causes AWFUL constipation. I was having to use Miralax every day as directed by my Rheumatologist. I wonder if I kicked it down to 600 and probioitics if I could still keep the migraines at bay but still use the potty with any regularity? Should I take the chance or just keep taking the mega dose of magnesium?
Do you take all 1,000 at once? What type of magnesium?
Yes it does cause this for me. But I was told to take 1000 because I have a deficiency. It usually only happens first thing in the morning. I just thought it was also helpful for me to lose weight. Is it harmful?
C Latts says
The problem with chronic diarrhea is that it doesn’t allow your body time to absorb many of the nutrients that were in the food or supplements you ate beforehand. This can cause deficiencies, and if you are taking vitamin/mineral supplements, for example, you are wasting your money by flushing them out before they can benefit you.
D.Nicole Uscher says
Have a home in the Bahamas with a well .Only drink bottled water from local water factory ,but have diarrhea every day sometimes three times a day and never know when .Not fun …found out that we have HARD WATER and is too full of minerals .Anything I can do about this ,we drink lot’s of water all the time to stay hydrated .
Devra Rossi says
Add two teaspoons of baking soda to each gallon of hard water. It alkalizes it and will make it better.
David Sharpe says
I think many of you are self-medicating without working with a doctor. Magnesium, while a “natural supplement” is a powerful chemical that works on neuro-transmitters and other complex nervous system functions. It’s great for migraines, cramps, sleep, anxiety, and much more, but you can really get your chemistry out of whack with it only, let alone taking it with other patent or OTC substances. Diarrhea itself can be a very dangerous side effect with bad long term damage. Spend the money, use your insurance, but see a doctor at least for a consult on using this. I take it for several neuro issues from having polio as a child and it’s fantastic for a variety of related things, but not “willy-nilly” without a least a little professional advice.
Andrew McVagh says
Great point David. Similar to you, it was my neurologist that recommended magnesium – I did not start it on my own.
Everyone should talk to a doctor first and not try to self-diagnose.
Travis Van Slooten says
On paper your suggestion makes perfect sense but the reality is, 95% of doctors don’t have a clue about magnesium. If you’re fortunate enough to find a good functional or integrative doctor in your area, then I agree it makes perfect sense to seek a doctor’s help first. The problem is, these types of doctors are extremely hard to find – especially if you live in a rural area.
As a result, we’re left to be our own doctors and experiment on our own. Fortunately, unless you have a kidney problem, magnesium is pretty safe to “experiment” with as long as you’re not over doing it.
I wish every run-of-the-mill family doctor was well-versed on supplements like magnesium. It would make life so much easier. Unfortunately, they are not.
franziska klaiber says
you are so right ! you can go to 20 docs and say you have sleep problems and anxiety and cramps (all could be signs of magnesium deficiency) but NO DOCTOR will see the connection…you wil go home with a sleep pill and anti anxiety drug.LOL
This is absolutely true. I’ve been getting insane migraines, anxiety, depression, insomnia and NO ONE put the clues together. Then I got the stomach flu 3 weeks ago, got dehydrated and the ambulance showed up just as my body went into a full spasm. My wrists turned in, my feet turned under me and I had no control over it. My magnesium was super low when they tested my blood. I’ve been taking 600mg of chelated Magnesium at bedtime and I can sleep! I haven’t had diarrhea yet, so I was suggested to go up to 800mg and see if I can tolerate it. I need to take the most that I am able for about 6 months to try to build some stores up! Magnesium is amazing stuff and I feel so much better already!
I heard that if a Dr checks your magnesium level they check it with a blood test. I also heard that if the body has a magnesium deficiency, the body will pull it from the bones or wherever else it may be to keep the levels up in the blood. So the blood work will most likely show no deficiency even though you are.
I agree with Travis. We are very often told to ask our doctor, but they are clueless. We are better off doing our own google search.
jawnee logik says
Show me a Western trained doctor that knows “thing-one” about nutrition and I will believe in the existence of unicorns!
Not sure anyone mentioned this already. Worth researching / testing on yourself: Epsom Salts baths. Mark Sisson would talk about this probably. Certainly I remember him linking out to a science study (as he always does) that suggested transdermal absorption is likely. Our grandmothers knew some stuff, right?
Devra Rossi says
Thanks for this!
Mary Jane Levell says
I have epilepsy and heard that people with epilepsy have too little magnesium. I take a lot, but I recently heard that too much magnesium is bad for kidneys. Is this true,?
I am taking Magnesium tabs 2 x daily 1000 MG. and have had diarrhea every day for over a month. Usually in the morning and then I am OK. Sometimes another time of the day as well.
I am taking an anti-diarrhea med (OTC) to counter it every other day but sometimes I cannot go more than one or two days with the OTC med.
Is it too much Magnesium I am taking?
You might be taking too much or the wrong kind. Just 5 mg for every pound of body weight.
So if you weigh 200 pounds you would take 1,000 mg. ONCE a day, not twice.
Magnesium Citrate causes Diarhea but there are other kinds.
David Sharpe says
My doctor, who is a magnesium fan for sleep, anxiety, depression, restless leg, muscle cramps, and more says: start with 400 mg magnesium glycinate and if no problems with diarrhea, go to 800 mg. If 800 is a problem, go back to 400 and stay there. She recommends more than 800 mg/day. However, she tells me that for maximum effect, one should increase the dosage until diarrhea is daily, then back off until your stools are normal. Then stay at this level. She prefers one take it in the evening, but with multiple tablets, taking 1/3 to 1/2 of the total in the morning is OK.
Hope this helps … sounds like you are taking much too much..
Julie Maliszewski says
Do you take 400 of ELEMENTAL magnesium or 400mg total magnesium. Please let me know. Thanks.
If you take calcium along with the magnesium it’ll counteract the diarrhea. Magnesium oxide is known to cause diarrhea more than any of the magnesium types. I took magnesium citrate 1300 mg and never had a problem but I now take 500 mg of magnesium oxide and it gives me diarrhea if I dont take calcium. The Citrate did not help me sleep but the Oxide does. So you can either change the type of magnesium you are taking or you can counteract the Mag oxide with calcium. So if you take 500 mg of mag oxide then take 500 mg of calcium. From what I read on the Internet the only people that can have a real problem with overdosing on magnesium is if you have kidney problems because the kidneys cannot flush out the excess your body does not use. But you do want to be careful, you’re dose seems kind of high to me. I suggest doing some research on the Internet. Hope this helped.
David Scott says
Im surprised that yoi didnt mention that caffeine / coffee lessens the amount of magnesium absorbed by the gut …so heres a thing – DONT DRINK COFFEE …or have just a little ????
Judy Jaeger says
I have been taking Magnesium Malate 100mg 3X day for several months without any problems. Today I added Magnesium L-Threonate 667mg before breakfast and within an hour I was running to the bathroom…..3 times…..
Will my body adjust to this or should I stop taking it immediately???
Just take a total of 5 mg per pound of body weight daily. No more.
Dee Fletcher says
I take 400mg of lindens magnesium per day, and it is listed as Oxide. My stools are loose and sometimes explosive, so am cutting back and will take on an empty stomach and break up the dosage as advised. If that doesn’t work I will try a better quality pill.
Yes…the runs. Had a colectomy last year so am loose anyway. After taking Mg tablet two days this week, I was really runny. So no Mg for me!
Hi I took one dose of magsmart and had diareaha . Magnesium always
Bothers me but I am having trouble with tight muscles . I’ve paid
$30 for this jar and can’t take it?
If I took half dose will
My body adjust ?
How much did you take in milligrams?
Rachael Nelson says
I only do 250 mg each night before going to bed since my 4 meds cause constipation !
I recently started taking magnesium 250 mg for migraine headaches. So far it has helped immensely but sometimes it does cause me diarrhea. I have been taking it before bed. Also I am taking a multi-vitamin which has 300 mg. of calcium and 100 mg magnesium. Do I need an additional calcium supplement to offset the magnesium or is this a good balance?
Hi, this isn’t exactly the same but I was prescribed Magnesium Citrate from my doctor for constipation, I took some yesterday and about 2 hours after it made me have diarrhea. I couldn’t bare the taste of the Magnesium Citrate so I didn’t take anymore today but yet I am still having to run to the toilet because it has now turned into watery diarrhea. How do I know when I am no longer constipated? And when will the diarrhea stop? And why do I have diarrhea? I know it sounds funny on why I am asking when will I know when I am no longer constipated but it has been so long since everything has been normal I forgot how it feels to not be constipated.
I’ve been taking Solaray magnesium glycerinate 400 MG, one daily for a week. Diarrhea every day. Stopped taking. Could this mean I have enough magnesium in my body?
Gina Parnell says
Hi! I started taking mag oxide, 1000 mg/day for osteopenia. I also have other health issues that I learned also have to do with mag deficiency, and after 1-1/2 weeks, the R.A. symptoms are virtually gone! But diarrhea set in. At first I thought it was my body being flushed of the excess calcium that has obviously built up, but after 6 days, I switched to citrate hoping to level out. It’s just day 1 so I’m not able to comment yet. Just keeping my fingers crossed. I’d like to be able to find a family physician or orthopedist to assist me in monitoring my rebuilding bone. Any suggestion as to which specialty would best serve me?
Sue L says
I have osteoporosis and I see an endocrinologist that does my blood work. You might have your gp refer you to one.
Devra Rossi says
Oxide is the worst mag ediu.. Try magnesium glycitate. Try taking lower dosages through out the day. I go on Amazon and look for the best rated by customers. I find it’s imperative to take with fiber and or with a glass of milk preferably or with water
Carlos Coronado says
I’ve been taking Magnesium supplement 500 mg. for the past week and since then I am having diarrhea bouts every day. The product I am using is from Sundown. Is it maybe that I am taking too much and could that be the reason of the diarrhea?
Any suggestion would be appreciated.
Does it have oxide in it. The OTCs with Oxide will cause diarrhea, according to my doctor.
Yes I got diarrhea due to intake of Mg.
Can you tell me if SUPRAVIT is ok??
That’s what i am taking
Hi Ijust took magnesium about a week and i have symptoms that diahheria,nausea,dizziness so what i do now should i go to doctor or is there anything will help me please tell me asap thank you for your time…
And also I’m taking iron,vitamin D.
Andrew McVagh says
Hi Neha. I would definitely suggest talking to a doctor. Iron in particular shouldn’t be taken without having your levels tested first as it can build up in your system over time.
I hope this helps!
This is not completely related to this article but this is the first post I have seen that was so close to giving me an answer.
I am a vegetarian and my diet is naturally high in magnesium. I only recently learned that’s why I have been having so much diahrea. I eat beans, almonds, and veggies like they are going out of style but I am trying to find a way to not cause me so much discomfort. I don’t take supplements. I definitely don’t need them. Is there any way to balance the magnesium?
I have been vegetarian for 17 years, i have found at times that the combinations i was eating caused something similar. I highly doubt your issue has anything to do with magnesium. What i strongly suggest is that you find a nice balance in your diet which you will start to feel yourself having ideal stool is a good indication of a balanced diet. I would start by increasing raw bananas, brown rice intake and go from there you can google foods that keep you solid etc. Just include enough of those and make sure you get vitamin C with every meal! this the key to vegetarianism, vitamin C is in almost every food in its raw state so simply eat something raw with every meal. If you are concerned about Iron at any stage consider a vitamin C suplement with your high iron meals before taking actual iron etc. Hope that’s helpful, there is abundant misinformation about vegetarianism. Listen to your body. =)
Cut back on beans they are very hard to digest. Try other proteins like quinoa which has a full range of amino acids.
Lorna Dyter says
I am using magnesium body butter but I think this is giving me diarrhoea, is there any way to stop this?
I have been takimg the calm. I take 2 tsp before bed and i love it. It calms me and helps me sleep. But it gives me diahrea. Do you have any suggestions? If i were to switch to the Best and the other one that helps you sleep, wouldnt that be too much magnesium. I really hate having to stop the calm though.
Hi Deborah. I agree that taking the calm with something else would probably be too much :)
When I first started taking magnesium I always made sure I was taking only one kind at a time. This way I could associate any good or bad outcomes with that particular magnesium. It was only later, when I knew how the best and the malate affected me, that I combined them.
So whenever I wanted to try a new one I first stopped the old one.
I hope that helps a bit!
shelly morris says
Hi, I have been following a Low Carb High Fat way of life for 2 years now. Up until last week I was fine but suddenly have developed muscle jitters in my legs (you can see them jumping about) I have these all day but especially at night. I understand that Magnesium is good for this but wondered which one was the best. I have read the Best Magnesium Supplement but am wondering do I take them all ?? or just one of them. I have purchased 2 days ago Magnesium Citrate and have so far taken 3 a day of these but they do not seem to be doing that much as I can feel my muscles still twitching but not to the extent they were before. Thank you for your answer in advance, Shelly Morris
My husband has been taking the magnesium crystals for a week, after 5days he had his first nights uninterrupted sleep. He has been having foot cramps for about 9months, but it did take just under a week for it to work, so persevere
Ronda Mcmillan says
The section you discussed covered my questions. Thanks for the information,looking forward to feeling better as I continue to take the calcium.
Hello, I have a question that isn’t about this article exactly. Well, would you happen to know if excessive thirst and dry mouth could be symptoms of magnesium deficiency as well? I don’t have diabetes because I have done blood work checking my blood sugar already. I do get low blood sugar when I don’t eat at my right times though. Also, I get the excessive thirst and hunger when it is time to eat. Especially, at night, sometimes I can’t sleep well because of the thirst. I do have other symptoms of magnesium deficiency, but I’m just wondering if thirst could be one too.
Hi Gisselle. Dry mouth looks to be associated with a wide range of ailments, and it seems like most medications list it as a side effect.
However, I did find something that talked about hypercalcemia, which is when there is too much calcium in the blood. Since magnesium and calcium regulate each other, I could see having too much calcium as maybe indicating too little magnesium. One of the symptoms of hypercalcemia is dry mouth and excessive thirst.
Has your doctor suggested a cause of the dry mouth? Did your blood work show your blood calcium levels?