Magnesium Supplements Guide: Forms Compared, How Much & What to Buy

Our pick, if you take magnesium

Revive MD Pure Magnesium Glycinate 200 mg

Check price on Amazon

Magnesium

200 mg a serving2 capsules, as glycinate

A day

$0.33Revive MD’s own price

Testing list

Informed Sportbatches tested for banned drugs

Bottle

60 servings, $19.99Revive MD’s own price

Our take

We pick it because it has the same 200 mg in 2 capsules as the rest of the glycinates we compare, is on the Informed Sport list (every batch is tested for drugs banned in sport), and costs less than half as much a day as Nature Made, the highest-scoring glycinate on our list. Glycinate is a form many people choose because it is gentle on the stomach. On the Informed Sport list: every batch is tested for drugs banned in sport. It is not a check of the label.

Testing record

• Informed Sport: Revive, Magnesium Glycinate, capsule. Every batch is tested for drugs banned in sport. It is not a contents check. See the listing

What magnesium does

• Helps more than 300 enzymes work. They control making protein, muscle and nerve function, blood sugar and blood pressure. Magnesium also helps build bone and keeps the heart beating in rhythm (NIH).
• How much you need. 400 to 420 mg a day for men and 310 to 320 mg for women, from food and pills together (NIH). How much magnesium per day, by age.
• Many people fall short. 48% of Americans get less than they need from food and drinks (NIH). True deficiency with symptoms is uncommon in healthy people, because the kidneys hold on to magnesium when intake is low.
• Best food sources. Pumpkin seeds (156 mg an ounce), chia seeds, almonds, spinach, cashews, peanuts, soymilk and black beans (NIH).

Who is likely to need more magnesium

• Older adults. They tend to eat less magnesium, absorb less from the gut and lose more in urine (NIH).
• People with type 2 diabetes. High blood sugar makes the kidneys lose more magnesium in urine (NIH).
• People with gut conditions. Crohn’s disease, celiac disease and long-term diarrhea lower absorption (NIH).
• People with alcohol use disorder. Low magnesium is common, from poor diet, vomiting, diarrhea and kidney losses (NIH).
• People on some long-term medicines. Heartburn pills (PPIs) taken for over a year, and loop or thiazide water pills, can lower magnesium (NIH).

A blood test is the usual check, but less than 1% of your magnesium is in your blood, so the test can look normal when your body is low (NIH). Ask your doctor if you are in one of these groups. Signs of low magnesium.

How much to take

The upper limit for adults is 350 mg a day of magnesium from supplements and medicines. Food does not count toward it (NIH).

Count every product you take, multivitamins too. We checked 833 magnesium labels: the median serving was 250 mg, but following the label’s directions took the median day to 399 mg, over the limit. Full dose guide, with a calculator.

Best form by goal

Leg cramps, anxiety and migraine: which form for each of 6 goals.

Magnesium forms compared

For most people, glycinate or citrate. Small studies found the citrate, aspartate, lactate and chloride forms absorbed better than oxide and sulfate (NIH). NIH says nothing about glycinate either way. Oxide packs the most magnesium into a pill but is absorbed less well. The chart below compares the forms: how much of each compound is magnesium, what NIH says, cost, and the top score in each form.

Scores compare products within one form, so these are the top score on a testing list in each form, or the top score where none is on a list. All 8 forms compared, or glycinate vs citrate head to head.

How to read a magnesium label

The “Magnesium” line on the Supplement Facts panel is the magnesium itself (the elemental amount), not the weight of the whole compound (NIH). The front often shows the whole compound. A label that says “2,000 mg magnesium glycinate” holds about 280 mg of magnesium. In April 2026, the advertising watchdog NAD reviewed a gummy sold as “200 mg per serving” whose panel showed 22 mg of magnesium; the brand agreed to change the claim (NAD). The case was brought by Pharmavite, which makes Nature Made.

Check the form in brackets too. Some “glycinate” products are blends with magnesium oxide. One we link says so on its label; in November 2025, Health Canada recalled two that did not (is your glycinate really glycinate?).

What magnesium helps with, and what it doesn’t

This is research, not advice for any condition. Talk to your doctor before using magnesium for a health problem.

• Sleep: a small effect, weak evidence. In 3 trials of 151 older adults with insomnia, people fell asleep about 17 minutes faster than on placebo; total sleep time did not change significantly. The evidence quality was low to very low (Mah 2021).
• Blood pressure: a small drop. Across 38 trials, magnesium lowered blood pressure by about 3 points (top number) and 2 points (bottom number). People with normal blood pressure saw no significant change (Argeros 2025). NIH calls the effect marginal.
• Migraine: “probably effective.” That is the rating neurology groups give it. The doses used are above the limit, so NIH says to use it only with a doctor’s guidance.
• Constipation: oxide helped in 2 trials. In 2 trials, 68% of people improved on magnesium oxide vs 19% on placebo (van der Schoot 2023).
• Leg cramps: probably not. A Cochrane review found magnesium unlikely to help typical cramps in older adults (Garrison 2020).
• Anxiety: promising, poor evidence. A review found results that suggest a benefit in people prone to anxiety, but rated the studies poor (Boyle 2017).

How long does magnesium take to work?

Trials measured results after weeks, not days. No trial we cite measured a same-night effect. The three sleep trials ran 3 to 8 weeks (Held 2002; Nielsen 2010; Abbasi 2012). The blood pressure trials lasted a median of 12 weeks (Argeros 2025), and an earlier review found that either 300 mg a day or about a month of use was enough to raise blood magnesium and lower blood pressure (Zhang 2016). If a symptom has not changed after a couple of months, talk to your doctor rather than raising the dose.

Side effects and cautions

• Diarrhea is the common one. Too much magnesium from pills most often causes diarrhea, sometimes with nausea and stomach cramps. That is why the limit is set where it is (NIH). The forms most often reported to cause it are carbonate, chloride, gluconate and oxide (NIH).
• Kidney disease. If you have kidney disease, ask your doctor before you take magnesium. Weak kidneys cannot clear the extra, so it can build up (NIH).
• Medicines. Antibiotics: take tetracyclines (such as doxycycline) or quinolones (such as ciprofloxacin) at least 2 hours before or 4 to 6 hours after magnesium (NIH). Osteoporosis drugs (bisphosphonates such as alendronate): take them at least 2 hours apart from magnesium (NIH).
• Too much. Dangerous levels are rare. They have mostly come from very large doses of magnesium laxatives or antacids, usually more than 5,000 mg a day (NIH).

Magnesium side effects, in full.

When to take magnesium

Any time of day works; what matters is taking it most days. Take it with a meal if it upsets your stomach, and space it from the antibiotics and osteoporosis drugs above. Many people take glycinate in the evening. Best time to take magnesium.

Which magnesium to buy

Buy magnesium that is on a public testing list. 4 of the 15 magnesium products we score are on one. Our pick, Revive MD Pure Magnesium Glycinate 200 mg, is on the Informed Sport list and is at the top of the page. Four more on a list:

1. USP Verified glycinate

   Nature Made Magnesium Glycinate 200mg
   8.0/10 · $0.73 a serving (200 mg) · USP Verified

   Check price for Nature Made Magnesium Glycinate 200mg

   200 mg of magnesium as glycinate in 2 capsules, $0.73 a day at list price. It has the top score of the glycinates we score.

2. A smaller capsule

   Thorne Magnesium Glycinate
   6.5/10 · $0.29 a serving (120 mg) · NSF/ANSI 173

   Check price for Thorne Magnesium Glycinate

   120 mg of magnesium as glycinate a capsule, so 1 or 2 a day. Its label allows up to 4 (480 mg), which is over the limit.

3. A USP Verified citrate

   Nature Made Magnesium Citrate 250 mg
   9.0/10 · $0.39 a serving (250 mg) · USP Verified

   Check price for Nature Made Magnesium Citrate 250 mg

   250 mg of magnesium as citrate in 2 softgels. It scores 9.0 in the citrate group.

4. If you want a gummy

   Nature Made Magnesium Glycinate Gummies 100 mg
   8.5/10 · $1.05 a serving (100 mg) · USP Verified

   Check price for Nature Made Magnesium Glycinate Gummies 100 mg

   100 mg of magnesium as glycinate in 2 gummies, much less than a capsule gives. Gummies we score hold 70 to 100 mg a serving; check the magnesium line on the panel.

The best magnesium supplements: all 15 we score, with each score, cost per 300 mg and testing list. Or which glycinates are third-party tested.

Other magnesium products we link

Cost is for 300 mg of magnesium at each brand’s own list price, so a 120 mg capsule and a 400 mg serving compare fairly. Scores compare products within one form only. All 18 magnesium products we track, ranked.

A dash under testing list means the product is on none of the five public lists we searched. BulkSupplements’ label says glycinate and oxide. KAL has no list price we could check.

Frequently asked questions

Magnesium guides

Sources

1. NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (functions, needs, food, intakes, groups at risk, absorption by form, labels, upper limit, side effects, toxicity, interactions, blood pressure, migraine; updated January 6, 2026; read October 14, 2026).
2. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults. BMC Complement Med Ther. 2021. PubMed 33865376
3. Schuster J, et al. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep. 2025. PubMed 40918053
4. Schuette SA, et al. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. JPEN J Parenter Enteral Nutr. 1994. PubMed 7815675
5. Held K, et al. Pharmacopsychiatry. 2002. PubMed 12163983. Abbasi B, et al. J Res Med Sci. 2012. PubMed 23853635. Nielsen FH, et al. Magnes Res. 2010. PubMed 21199787
6. Argeros Z, et al. Magnesium supplementation and blood pressure. Hypertension. 2025. PubMed 41000008
7. Zhang X, et al. Effects of magnesium supplementation on blood pressure. Hypertension. 2016. PubMed 27402922
8. van der Schoot A, et al. The effect of food, vitamin, or mineral supplements on chronic constipation in adults: a systematic review and meta-analysis of randomized controlled trials. Neurogastroenterol Motil. 2023. PubMed 37243443
9. Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020. PubMed 32956536
10. Boyle NB, et al. The effects of magnesium supplementation on subjective anxiety and stress: a systematic review. Nutrients. 2017. PubMed 28445426
11. BBB National Programs, National Advertising Division. Nature’s Truth magnesium glycinate gummies (April 27, 2026). Health Canada recall of Life Brand Magnesium Bisglycinate 200mg (November 12, 2025).
12. NIH Dietary Supplement Label Database, 833 magnesium labels read August 29, 2026; our analysis.

This page is for information. It is not medical advice.