Magnesium glycinate is usually well tolerated at label doses, with looser stools, nausea or drowsiness the most common effects, while serious problems are rare and mostly linked to very high intakes or reduced kidney function.
What magnesium glycinate is, and why the dose matters
Magnesium glycinate is magnesium bound to glycine, an amino acid. The Stack's Deep Rest capsule uses magnesium bisglycinate as its only active ingredient. The label lists 92.2 mg of elemental magnesium per capsule, and that figure, not the weight of the whole capsule, is what counts toward your daily total. The suggested use is one capsule a day, taken 30 to 60 minutes before bedtime.
Side effects follow the dose more closely than the form. Most of what's known about digestive effects comes from higher doses and from magnesium salts used as laxatives and antacids, so the sections below separate what's common at everyday supplement amounts from what needs medical attention.
Common side effects: looser stools, nausea and cramps
Digestive effects are the most common problem, mainly diarrhoea or looser stools, and they're more likely at higher doses. They're usually mild and ease once you cut back.
The form matters to a degree. Magnesium carbonate, chloride, gluconate and oxide are the forms most often linked with diarrhoea. Glycinate isn't on that list, which is one reason it's usually described as gentler on the stomach. Direct comparisons are few, so treat "gentler" as a reasonable expectation rather than a certainty.
Magnesium bisglycinate taken daily by adults with poor sleep caused few side effects, and none serious.
Dose matters a great deal. At 600 mg of magnesium a day, taken as a different salt (trimagnesium dicitrate), some people had diarrhoea and stomach irritation. That dose is well above the 350 mg supplemental limit discussed below.
Drowsiness after an evening dose
Some people feel relaxed or drowsy after an evening dose. For many, that's the reason they take it at night, and it's usually mild. Drowsiness becomes a warning sign when it's severe, when it comes with confusion or weakness, or when it appears alongside a slow or irregular heartbeat. Those symptoms can accompany high magnesium levels.
A light snack or meal beforehand may ease stomach upset. That's practical advice, and it doesn't change the dose. As with any evening product, avoid combining it with alcohol or sedating medicines.
Recommended Products
If you want magnesium from a capsule, these are the two options in The Stack range. If you use both, count the magnesium from each.
Rare effects: toxicity and allergic reactions
Serious reactions are uncommon at normal supplement amounts. The main concern is magnesium toxicity, which shows up as low blood pressure, irregular heartbeat and, in the most severe cases, cardiac arrest.1 It's usually linked to very large intakes, such as magnesium-containing laxatives and antacids that provide more than 5,000 mg a day, or to kidneys that can't clear the excess.
A few fatal cases have been reported, almost always with the largest doses from laxatives and antacids, and more likely when kidney function is reduced. Allergic reactions are rare. Stop taking the product and seek urgent help if you notice swelling of the face, lips, tongue or throat, difficulty breathing, or a rash with hives.
The 350 mg upper limit, and how to count it
The upper limit for supplemental magnesium is 350 mg a day for adults. It counts magnesium from supplements and medicines only. Magnesium in food isn't counted, because healthy kidneys clear the excess. The limit exists because digestive effects become more likely at higher supplemental amounts.
Counting is simple for Deep Rest. One capsule of magnesium bisglycinate provides 92.2 mg, which leaves room under the limit. Four capsules would provide about 369 mg, which is already above 350 mg before any other magnesium product is counted. That's why the label dose matters, and why you shouldn't increase the amount on your own.
| Source | Example | Counts toward 350 mg? |
|---|---|---|
| Food | Nuts, seeds, leafy greens, whole grains | No |
| Magnesium supplement | One Deep Rest capsule (92.2 mg) | Yes |
| Combination product | The Complete Sleep Stack, which includes a Deep Rest capsule | Yes |
| Multivitamin or mineral tablet | Any product that lists magnesium | Yes |
| Medicine | Magnesium-containing antacids and laxatives | Yes |
The limit is lower for children: 65 mg at ages 1 to 3, 110 mg at ages 4 to 8, and 350 mg at ages 9 to 18. Deep Rest is labelled for adults, so don't give an adult capsule to a child without a doctor's direction.
Who should avoid it, and who should check first
Who should avoid it unless a doctor says otherwise
- People with kidney disease or reduced kidney function. The kidneys clear extra magnesium, so when they can't, levels can build up. In people with chronic kidney disease, magnesium raised blood magnesium and brought more digestive problems and more serious events.2 Anyone with kidney problems needs medical supervision before any magnesium product.
- People with heart block. A conduction problem in the heart is a reason to avoid magnesium supplements unless a doctor is supervising them.
- People with a bowel obstruction or other serious bowel disorders. Magnesium salts act as a laxative, so they can make these conditions worse.
Who should check first
Check first if any of these apply.
| Situation | Why it matters | What to do |
|---|---|---|
| Heart rhythm problems, or heart medicines such as digoxin | Magnesium affects the heart's electrical activity, and magnesium products can interact with heart drugs. | Check with your cardiologist before starting. |
| Antibiotics, such as doxycycline, tetracycline, ciprofloxacin or levofloxacin | Magnesium binds these antibiotics in the gut and can reduce how much they absorb.1 | Take the antibiotic at least 2 hours before, or 4 to 6 hours after, magnesium. Confirm the schedule with a pharmacist. |
| Thyroid medicine (levothyroxine) | Some magnesium forms reduce how much levothyroxine your body takes in. Glycinate hasn't been tested.3 | Separate the two doses, and ask your prescriber how far apart to take them. |
| Bisphosphonates for osteoporosis, such as alendronate | Magnesium reduces absorption of these drugs when taken too close together. | Keep at least 2 hours between them. |
| Diuretics, or long-term acid-reducing medicines (PPIs) | Diuretics change how much magnesium you lose in urine, and long-term PPI use can lower magnesium levels. | Ask about magnesium testing and dosing. |
| Diabetes medicines, especially sulphonylureas | Magnesium can add to the blood-sugar-lowering effect of these drugs. | Check before starting. |
| Pregnancy or breastfeeding | Pregnancy and breastfeeding are reasons to tell your care team before use, so the dose should be agreed with them. | Ask your doctor or midwife first. |
| Food allergies | Deep Rest is processed on equipment that also handles soy, dairy, wheat and other nuts. | Read the allergen statement on the pack before you buy. |
Signs of too much magnesium
Looser stools, nausea and cramps are the usual early signs of too much supplemental magnesium. They're unpleasant but not usually dangerous on their own. Stop the supplement if they continue or get worse.
More serious signs are low blood pressure, vomiting, facial flushing, difficulty passing urine, lethargy and depression. As levels rise, muscle weakness, difficulty breathing, irregular heartbeat and cardiac arrest can follow.
Reducing side effects and avoiding double dosing
- Stick to the label dose. Don't add extra capsules because you want a stronger effect.
- Count combination products. The Complete Sleep Stack includes a Deep Rest magnesium capsule with a glycine serving, so taking a separate magnesium capsule on top would double the magnesium.
- Reduce or pause if stools stay loose. Persistent loose stools are a signal to cut back before restarting.
- Check the timing. For when to take it through the day, read the guide to the best time to take magnesium glycinate.
Buying magnesium glycinate in India
Indian labels can make the dose hard to judge. Check the elemental magnesium per serving, which is the figure that counts toward the 350 mg limit, not the total weight of the compound. A label that gives only the compound weight makes it hard to add up your intake.
Packaged foods and supplements sold in India must carry the FSSAI logo and a licence number, so look for both on the pack. Also check the batch number, manufacture date and best-before date, and read the allergen statement if you have a food allergy.
Frequently Asked Questions
Does magnesium glycinate cause diarrhoea?
It can, mainly at higher amounts. Glycinate isn't among the forms most often linked with diarrhoea, but it can still cause loose stools. If they persist, reduce the amount or pause.
Will it make me drowsy?
Mild drowsiness after an evening dose is reported by some people. Severe sleepiness, confusion or weakness isn't expected and needs medical help.
How much is too much?
For adults, the upper limit is 350 mg a day from supplements and medicines combined. Food doesn't count toward that limit.
Can I take it with antibiotics?
Only with spacing. For doxycycline, tetracycline, ciprofloxacin and levofloxacin, take the antibiotic at least 2 hours before, or 4 to 6 hours after, magnesium. Confirm your schedule with a pharmacist.
Can I take it with levothyroxine?
Ask your prescriber how far apart to take them. Magnesium can lower how much levothyroxine your body absorbs, so the two should be taken apart, especially when thyroid levels need to stay within a narrow range.
Is it safe if I have kidney disease?
Not without medical supervision. Reduced kidney function makes it harder to clear magnesium, so a doctor should decide whether it's appropriate and how to monitor it.
Is it safe during pregnancy or breastfeeding?
Check with your doctor or midwife first. The dose should be agreed with them rather than set by the label alone.
What should I do if I take too much?
Stop the supplement. If you have muscle weakness, fainting, trouble breathing, a slow or irregular heartbeat or confusion, seek emergency care at once.
Disclaimer: This article is general information about magnesium glycinate. It does not diagnose, treat, cure or prevent any condition. Talk with a doctor or pharmacist before starting a magnesium supplement, especially if you are pregnant or breastfeeding, have kidney or heart problems, have a bowel disorder, or take regular medicines.
References
- National Institutes of Health, Office of Dietary Supplements. Magnesium: Health Professional Fact Sheet. Authority guidance. ods.od.nih.gov (accessed 4 November 2026).
- Bressendorff I, Hansen D, et al. The Effect of Magnesium Supplementation on Vascular Calcification in CKD: A Randomized Clinical Trial (MAGiCAL-CKD). J Am Soc Nephrol. 2023 May. doi:10.1681/ASN.0000000000000092. PMID: 36749131. PubMed
- Attinger MC, von Felten S, Rodrigues CL, et al. Single Center, Open-Label, Randomized Crossover Trial on Drug-Drug Interactions of Levothyroxine/Magnesium-Citrate and Levothyroxine/Magnesium-Aspartate in Healthy Subjects: The ThyroMag Trial. Clin Transl Sci. 2025 Nov. doi:10.1111/cts.70409. PMID: 41221788. PubMed
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