Most people don't notice any side effects from magnesium glycinate, one of the gentlest forms of magnesium. When they do show up, the usual ones are loose stools, nausea and stomach cramps, typically from a high dose or from a "glycinate" that's buffered with magnesium oxide. Serious problems are rare in healthy adults and mostly come from very high doses or reduced kidney function.
In this article
- Common magnesium glycinate side effects
- Why does magnesium glycinate give me diarrhea?
- Can magnesium glycinate cause vivid dreams?
- Magnesium glycinate keeps me awake: is that possible?
- Does magnesium glycinate turn your urine yellow?
- How much magnesium is too much?
- Kidneys, medications and pregnancy
- How to keep side effects to a minimum
- Quick answers
- Sources
I'd rather you know what's normal before you start. Below: the common side effects and what to do about them, the questions people search at 2 a.m. (vivid dreams, feeling wired, bright yellow urine), the signs that aren't normal, and who should check with a clinician first.
Common magnesium glycinate side effects
According to the NIH Office of Dietary Supplements, high doses of magnesium from supplements or medicines can cause diarrhea, nausea and abdominal cramping. Those are the side effects you'll see most, with any form. Glycinate is popular because it tends to cause them less often than some other forms, and our guide to magnesium glycinate vs citrate vs oxide explains why.
“When I was researching different forms of magnesium, glycinate stood out to me because it's known for being gentle and well tolerated. That was really important to me when we were creating NO. 04.”
Skotie Rae, RN, founder
| What you notice | Usually normal? | What to try |
|---|---|---|
| Looser stools the first week | Yes | Take it with food, or split the dose between dinner and bedtime |
| Mild nausea | Yes | Take it with a meal and a full glass of water |
| Morning grogginess | Can happen | Take it earlier, with dinner |
| Feeling more alert at night | Sometimes | Move it to the morning |
| Ongoing diarrhea, vomiting, weakness, a slow or irregular heartbeat | No | Stop and call your clinician; get urgent care for severe symptoms |
Why does magnesium glycinate give me diarrhea?
Magnesium that isn't absorbed pulls water into the bowel. That's how magnesium laxatives work. The less of a dose your body absorbs, the more is left in the gut to do it. Two things make it more likely:
- A big dose all at once. Splitting it, or taking it with food, often solves this.
- A buffered product. Plenty of "glycinate" labels are blended with magnesium oxide, which is poorly absorbed. In one comparison of U.S. preparations, oxide had a fractional absorption of about 4% (Firoz and Graber, 2001). If your glycinate bothers your stomach, look at the words in parentheses on the Supplement Facts panel. Our guide to buffered vs non-buffered magnesium glycinate shows you what to look for.
Can magnesium glycinate cause vivid dreams?
People ask about this constantly on forums, and there's almost no research on it. Some people remember more dreams when they start any new evening supplement, which may just be because they're sleeping differently or waking at different times. If the dreams bother you, take it earlier in the evening and jot down what you notice for a week or two. There's no evidence that it signals harm.
Magnesium glycinate keeps me awake: is that possible?
It's uncommon, but people do report it. Magnesium isn't a sedative and won't knock you out, and a few people feel more alert after taking a new supplement at night. The fix is easy: take it in the morning instead. There's no single right time, and taking it consistently matters more than the hour. Our guide to when to take magnesium glycinate has more on timing.
Does magnesium glycinate turn your urine yellow?
Not usually. Bright yellow urine is almost always riboflavin (vitamin B2), which is naturally yellow and shows up in most multivitamins and B-complex supplements. The NIH notes that your body can absorb only about 27mg of riboflavin at a time, so the extra passes into your urine, and riboflavin hasn't been shown to cause harm. If you started magnesium and a multivitamin the same week, that's probably your answer. Dark urine is different and can mean you need more fluids.
How much magnesium is too much?
The NIH sets the Tolerable Upper Intake Level for magnesium from supplements and medicines at 350mg a day for adults. Magnesium from food doesn't count toward it. Very high doses, usually from large amounts of magnesium-containing laxatives or antacids, can cause magnesium toxicity. The NIH lists low blood pressure, vomiting, difficulty breathing, irregular heartbeat and, rarely, cardiac arrest.
That's a very different situation from a daily 200mg supplement. It's still why I tell people to add up every source. A multivitamin, a sleep blend, an antacid and a "calm" drink can each carry magnesium, and they add up faster than you'd think.
Kidneys, medications and pregnancy
Your kidneys keep magnesium in balance by clearing the extra into your urine. That's why magnesium should be used with caution in people with kidney disease (Guerrera and colleagues, 2009). If you have kidney disease or have been told your kidney function is reduced, don't start any magnesium supplement without your clinician's okay.
The NIH also notes that magnesium can interact with oral bisphosphonates (osteoporosis medicines) and with tetracycline and quinolone antibiotics, and that diuretics and proton pump inhibitors can change your magnesium levels. Usually the answer is spacing the doses apart, and your pharmacist can map out that schedule with you quickly. If you're pregnant or breastfeeding, check with your clinician before starting.
How to keep side effects to a minimum
- Choose a non-buffered glycinate, so you aren't also getting oxide.
- Compare elemental magnesium, and stay within 350mg a day from supplements.
- Take it with food if your stomach is sensitive.
- Split the dose if one sitting is too much.
- Start one new supplement at a time, so you can tell what's causing what.
We made NO. 04 Magnesium Glycinate with that list in mind: 200mg of elemental magnesium from 1,700mg of Chelamax non-buffered magnesium bisglycinate, in three capsules you can split up, with no oxide and only three ingredients. Every lot is third-party tested, and the results are on our Certificate of Analysis page. Every product number is also on our Rae Basics facts page.
Quick answers
What are the most common side effects of magnesium glycinate?
Loose stools, nausea and stomach cramps, mostly at higher doses. Glycinate tends to cause them less often than oxide or citrate.
Why does my magnesium glycinate upset my stomach?
The dose may be too high for you, you may be taking it on an empty stomach, or the product may be buffered with magnesium oxide. Try it with food, split the dose, and check the label.
Can magnesium glycinate cause vivid dreams?
Some people report it, but there's almost no research. If it bothers you, take it earlier in the evening.
Is it safe to take magnesium glycinate every day?
For most healthy adults, yes, within the 350mg a day upper limit for supplemental magnesium. Talk to your clinician first if you have kidney disease, are pregnant or take prescription medicines.
What are signs of too much magnesium?
Diarrhea is usually the first sign. Very high doses can cause vomiting, low blood pressure, trouble breathing and an irregular heartbeat. Stop taking it and get medical help for severe symptoms.
Sources
- NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Riboflavin: Fact Sheet for Consumers.
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001;14(4):257-262.
- Guerrera MP, Volpe SL, Mao JJ. Therapeutic uses of magnesium. Am Fam Physician. 2009;80(2):157-162.
