Magnesium chloride
Also called MgCl2, magnesium chloride hexahydrate, magnesium oil, magnesium flakes, liquid magnesium chloride. One of 9 forms of magnesium compared on this page.
Grade C for chloride itself: metabolic syndrome and its components in adults with low magnesium Mineral Last checked
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The short answer
From 17 sourcesMagnesium chloride is one of the better-absorbed magnesium salts, according to NIH's Office of Dietary Supplements. Most of its trials come from one Mexican group studying adults with low blood magnesium, who saw lower glucose, insulin resistance and blood pressure (grade C). In one small trial in regular exercisers it slightly lowered exercise performance. Topical magnesium oil lacks controlled evidence.
Quick pick
From a partner brand · paid link
Nutricost Magnesium Chloride powder, unflavoured, 2 lb
from HerbsPro
Label: 1 scoop (1.9 g): 210 mg magnesium from 1,900 mg magnesium chloride hexahydrate (label).
Best for trying one bottle: $24.95 one-time (checked Oct 15, 2026).
Every graded outcome on this page
12 rows · line = participants- CGrade CMetabolic syndrome and its components in adults with low magnesiumTested chloriden 198
- CGrade CMild-to-moderate depression and anxiety symptomsTested chloriden 126
- CGrade CFasting glucose in prediabetes with low magnesiumTested chloriden 116
- CGrade CBlood pressure in people with diabetes, high blood pressure and low magnesiumTested chloriden 82
- CGrade CInsulin resistance and HbA1c in type 2 diabetes with low magnesiumTested chloriden 63
- CGrade CC-reactive protein in prediabetes with low magnesiumTested chloriden 62
- CGrade CInsulin resistance and blood pressure in metabolically obese, normal-weight adultsTested chloriden 47
- DGrade DDepressive symptoms after COVID-19 in adults with low magnesium and vitamin DTested chloriden 60
- DGrade DQuality of life in fibromyalgia with topical magnesium chloride sprayTested chloriden 40
- DGrade DDepression in older adults with type 2 diabetes and low magnesiumTested chloriden 23
- DGrade DHeart rhythm in congestive heart failureTested chloriden 21
- DGrade DCycling performance in regular exercisersTested chloriden 15
Key facts
- Absorption
- ODS: small studies find magnesium chloride, citrate, aspartate and lactate better absorbed than magnesium oxide or sulfate1
- Elemental magnesium
- About 12% of magnesium chloride hexahydrate by weight is magnesium (25.5% for the anhydrous salt), so labels should state elemental magnesium1213
- Upper limit
- 350 mg/day of supplemental magnesium for adults; chloride is among the forms most often reported to cause diarrhea1
- Who was studied
- Most trials enrolled adults with low serum magnesium, so results may not apply to people with normal levels457814
- Topical use
- A 2017 review concluded that claims for transdermal magnesium (sprays, flakes, salt baths) are scientifically unsupported12
- Largest trial
- 198 adults with metabolic syndrome and low magnesium: fewer still met metabolic-syndrome criteria after 16 weeks (48% vs 77.5%)14
What it is
Magnesium chloride is a water-soluble magnesium salt sold as powder, liquid and topical 'magnesium oil', usually as the hexahydrate.
How it works
EstablishedMagnesium is a cofactor in more than 300 enzyme systems, including those that regulate blood glucose control and blood pressure. ODS notes that low magnesium may worsen insulin resistance and that diabetes increases urinary magnesium losses, which fits trials showing benefit mainly in people starting with low levels.1
Compound weight to elemental magnesium
Arithmetic, not advice60mg elemental magnesium500 mg magnesium chloride (oral powder, tablets or liquid) × 12%
Every magnesium form, side by side
9 forms named in our sources, each with a page of its own. Citation numbers in a column link to the page that holds them.
Magnesium forms compared
9 forms · 9 with a page · Chloride highlighted| 9 forms | ChlorideYou are here | Glycinate (bisglycinate)Read the page | CitrateRead the page | L-threonateRead the page | MalateRead the page | TaurateRead the page | OxideRead the page | OrotateRead the page | Sulfate (Epsom salt)Read the page |
|---|---|---|---|---|---|---|---|---|---|
| Elemental shareOf compound weight | 12%213Magnesium chloride hexahydrate MgCl2·6H2O, MW 203.30 (anhydrous MgCl2, MW 95.21, is 25.5% magnesium) | 14.1%10Mg(C2H4NO2)2, anhydrous MW 172.42 | 16.2%12Mg3(C6H5O7)2 (trimagnesium dicitrate), anhydrous MW 451.12 | 8.3%5Mg(C4H7O5)2, anhydrous MW 294.50 | 15.5%19MgC4H4O5, anhydrous MW 156.38 | 8.9%20Mg(C2H6NO3S)2, anhydrous MW 272.6 | 60.3%6MgO, MW 40.305 | 6.6%26Dihydrate C10H10MgN4O10, MW 370.51 (6.6% Mg); anhydrous C10H6MgN4O8, MW 334.48 (7.3% Mg); Mg 24.305 g/mol | 9.9%12MgSO4·7H2O: 24.3 ÷ 246.5 = 9.9% magnesium; the label gives 495 mg magnesium per 5 g teaspoon |
| Form-specific evidenceOutcomes tested on this form | CGrade CMetabolic syndrome and its components in adults with low magnesiumTested this formRCT, n 198, 2018 CGrade CMild-to-moderate depression and anxiety symptomsTested this formCrossover RCT, n 126, 2017 +10 more on its page | CGrade CInflammation markers and lung function in asthma and COPDTested this formRCT, n 224, 2026 CGrade CInsomnia severityTested this formRCT, n 155, 2025 +1 more on its page | CGrade CArterial stiffness and blood pressureTested this formRCT, n 164, 2022 CGrade CMigraine attack frequencyTested this formRCT, n 81, 1996 +4 more on its page | CGrade COverall cognitive performanceTested this formRCT, n 100, 2025 CGrade COpioid dose needed for pain in advanced cancerTested this formRCT, n 83, 2023 +2 more on its page | No form-specific graded outcome yet | No form-specific graded outcome yet | BGrade BOverall improvement in chronic constipationTested this formRCT, n 90, 2021 BGrade BOverall improvement in chronic constipationTested this formRCT, n 34, 2019 +2 more on its page | CGrade CHeart-rhythm, blood-pressure and related problemsTested this formMeta-analysis, n 1,190, 2015 CGrade CSurvival and symptoms in severe heart failureTested this formRCT, n 79, 2009 +2 more on its page | BGrade BFunctional constipation in women (mineral water)Tested this formRCT, n 244, 2014 BGrade BTreatment response in functional constipation (mineral water)Tested this formRCT, n 226, 2019 +4 more on its page |
| Studied dosesRange in its trials | 248–450mgElemental magnesium per day as stated in the oral trials13481415 | 100–250mgelemental magnesium (as glycinate/bisglycinate)342827 | 290–600mgelemental magnesium (as citrate)61522212310 | 83–165mgelemental magnesium (1–2 g/day of magnesium L-threonate compound)534192 | 250–600mgmg of elemental magnesium per day (with malic acid)361 | 121mgmg of elemental magnesium per day3 | 500–1,500mgmg of magnesium oxide (compound) per day834512 | 1,878–6,000mgmg of magnesium orotate compound per day (not elemental magnesium)347 | No data yet |
| Absorption in people | ODS: small studies find chloride, citrate, aspartate and lactate absorbed more completely than oxide or sulfate.1 | Similar to oxide overall in 12 ileal-resection patients (23.5% vs 22.8%); higher in the 4 poorest oxide absorbers.11 | Beat oxide on urinary and serum magnesium in short human studies.1314 | No human head-to-head data; rat data only.16 | No human comparison; highest serum AUC of five compounds in rats.22 | No human data; fast absorption and highest brain levels in rats (acetyl taurate).22 | About 4% fractional absorption in one comparison, the lowest tested.2113 | No head-to-head human absorption data in our sources.1 | Acts mainly in the bowel as an osmotic laxative: it keeps water in the large bowel and speeds transit.178 |
| GI tolerance | ODS lists chloride among the forms most commonly reported to cause diarrhea at high doses.1 | All 12 crossover patients tolerated it better than oxide.11 | Diarrhea in 18.6% at 600 mg/day (12-week migraine trial).15 | Well tolerated at 1–2 g/day for 3–6 weeks.1718 | No form-specific human data. | No serious adverse events in one 3-month study (taurate with potassium citrate).23 | Among the forms ODS links most often to diarrhea.1 | Large magnesium doses from supplements commonly cause diarrhoea, nausea and abdominal cramping.1 | Works as a laxative within 30 minutes to 6 hours; the label warns against use with kidney disease, a magnesium-restricted diet or abdominal pain, nausea or vomiting.1 |
| Studied for | Glucose, insulin resistance, blood pressure and CRP in adults with low magnesium; depression symptoms; heart rhythm in heart failure. | Insomnia severity (one RCT). | Arterial stiffness (no effect), bone turnover, migraine. | Cognition and sleep (small RCTs). | Fibromyalgia (one small trial). | Blood pressure (one uncontrolled study). | Constipation, migraine; arterial stiffness null. | Heart failure, heart rhythm and blood pressure (Russian trials) | Occasional constipation (OTC label); transit studies (D) |
- Magnesium chlorideYou are here
- Elemental share
- 12%213Magnesium chloride hexahydrate MgCl2·6H2O, MW 203.30 (anhydrous MgCl2, MW 95.21, is 25.5% magnesium)
- Form-specific evidence
- CGrade CMetabolic syndrome and its components in adults with low magnesiumTested this formRCT, n 198, 2018CGrade CMild-to-moderate depression and anxiety symptomsTested this formCrossover RCT, n 126, 2017+10 more on its page
- Absorption in people
- ODS: small studies find chloride, citrate, aspartate and lactate absorbed more completely than oxide or sulfate.1
- GI tolerance
- ODS lists chloride among the forms most commonly reported to cause diarrhea at high doses.1
- Studied for
- Glucose, insulin resistance, blood pressure and CRP in adults with low magnesium; depression symptoms; heart rhythm in heart failure.
- Magnesium glycinate (bisglycinate)Read the page
- Elemental share
- 14.1%10Mg(C2H4NO2)2, anhydrous MW 172.42
- Form-specific evidence
- CGrade CInflammation markers and lung function in asthma and COPDTested this formRCT, n 224, 2026CGrade CInsomnia severityTested this formRCT, n 155, 2025+1 more on its page
- Absorption in people
- Similar to oxide overall in 12 ileal-resection patients (23.5% vs 22.8%); higher in the 4 poorest oxide absorbers.11
- GI tolerance
- All 12 crossover patients tolerated it better than oxide.11
- Studied for
- Insomnia severity (one RCT).
- Magnesium citrateRead the page
- Elemental share
- 16.2%12Mg3(C6H5O7)2 (trimagnesium dicitrate), anhydrous MW 451.12
- Form-specific evidence
- CGrade CArterial stiffness and blood pressureTested this formRCT, n 164, 2022CGrade CMigraine attack frequencyTested this formRCT, n 81, 1996+4 more on its page
- GI tolerance
- Diarrhea in 18.6% at 600 mg/day (12-week migraine trial).15
- Studied for
- Arterial stiffness (no effect), bone turnover, migraine.
- Magnesium L-threonateRead the page
- Elemental share
- 8.3%5Mg(C4H7O5)2, anhydrous MW 294.50
- Form-specific evidence
- CGrade COverall cognitive performanceTested this formRCT, n 100, 2025CGrade COpioid dose needed for pain in advanced cancerTested this formRCT, n 83, 2023+2 more on its page
- Absorption in people
- No human head-to-head data; rat data only.16
- Studied for
- Cognition and sleep (small RCTs).
- Magnesium malateRead the page
- Magnesium taurateRead the page
- Elemental share
- 8.9%20Mg(C2H6NO3S)2, anhydrous MW 272.6
- Form-specific evidence
- No form-specific graded outcome yet
- Studied doses
- 121mgmg of elemental magnesium per day3
- Absorption in people
- No human data; fast absorption and highest brain levels in rats (acetyl taurate).22
- GI tolerance
- No serious adverse events in one 3-month study (taurate with potassium citrate).23
- Studied for
- Blood pressure (one uncontrolled study).
- Magnesium oxideRead the page
- Elemental share
- 60.3%6MgO, MW 40.305
- Form-specific evidence
- BGrade BOverall improvement in chronic constipationTested this formRCT, n 90, 2021BGrade BOverall improvement in chronic constipationTested this formRCT, n 34, 2019+2 more on its page
- GI tolerance
- Among the forms ODS links most often to diarrhea.1
- Studied for
- Constipation, migraine; arterial stiffness null.
- Magnesium orotateRead the page
- Elemental share
- 6.6%26Dihydrate C10H10MgN4O10, MW 370.51 (6.6% Mg); anhydrous C10H6MgN4O8, MW 334.48 (7.3% Mg); Mg 24.305 g/mol
- Form-specific evidence
- CGrade CHeart-rhythm, blood-pressure and related problemsTested this formMeta-analysis, n 1,190, 2015CGrade CSurvival and symptoms in severe heart failureTested this formRCT, n 79, 2009+2 more on its page
- Absorption in people
- No head-to-head human absorption data in our sources.1
- GI tolerance
- Large magnesium doses from supplements commonly cause diarrhoea, nausea and abdominal cramping.1
- Studied for
- Heart failure, heart rhythm and blood pressure (Russian trials)
- Magnesium sulfate (Epsom salt)Read the page
- Elemental share
- 9.9%12MgSO4·7H2O: 24.3 ÷ 246.5 = 9.9% magnesium; the label gives 495 mg magnesium per 5 g teaspoon
- Form-specific evidence
- BGrade BFunctional constipation in women (mineral water)Tested this formRCT, n 244, 2014BGrade BTreatment response in functional constipation (mineral water)Tested this formRCT, n 226, 2019+4 more on its page
- Studied doses
- No data yet
- Absorption in people
- Acts mainly in the bowel as an osmotic laxative: it keeps water in the large bowel and speeds transit.178
- GI tolerance
- Works as a laxative within 30 minutes to 6 hours; the label warns against use with kidney disease, a magnesium-restricted diet or abdominal pain, nausea or vomiting.1
- Studied for
- Occasional constipation (OTC label); transit studies (D)
What the human research says
Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.
Grade C for chloride itself. 12 outcomes on this page were tested with chloride: metabolic syndrome and its components in adults with low magnesium; mild-to-moderate depression and anxiety symptoms; fasting glucose in prediabetes with low magnesium; blood pressure in people with diabetes, high blood pressure and low magnesium; insulin resistance and hba1c in type 2 diabetes with low magnesium; c-reactive protein in prediabetes with low magnesium; insulin resistance and blood pressure in metabolically obese, normal-weight adults; depressive symptoms after covid-19 in adults with low magnesium and vitamin d; quality of life in fibromyalgia with topical magnesium chloride spray; depression in older adults with type 2 diabetes and low magnesium; heart rhythm in congestive heart failure; cycling performance in regular exercisers (RCT, n 198, 2018). For the overall evidence, see the Magnesium page.
Trial map
12 graded outcomes, largest study first12 graded outcomes: 11 improved, 1 worsened. The largest, a 2018 randomized trial of 198 people on metabolic syndrome and its components in adults with low magnesium, found an improvement. One outcome found a worsening: cycling performance in regular exercisers (15 people).
1Metabolic syndrome and its components in adults with low magnesium
Improved · Grade C · RCT, 198 people, 2018
Adults with metabolic syndrome and low serum magnesium (Mexico)
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Metabolic syndrome and its components in adults with low magnesium | Improved | 198 | Grade C · RCT, 2018 | Adults with metabolic syndrome and low serum magnesium (Mexico) |
| Mild-to-moderate depression and anxiety symptoms | Improved | 126 | Grade C · Crossover RCT, 2017 | Adults in US primary care with PHQ-9 scores of 5 to 19 (mean age 52) |
| Fasting glucose in prediabetes with low magnesium | Improved | 116 | Grade C · RCT, 2015 | Adults aged 30 to 65 with new prediabetes and low serum magnesium (Mexico) |
| Blood pressure in people with diabetes, high blood pressure and low magnesium | Improved | 82 | Grade C · RCT, 2009 | Adults aged 40 to 75 with type 2 diabetes and hypertension on captopril, with low serum magnesium (Mexico) |
| Insulin resistance and HbA1c in type 2 diabetes with low magnesium | Improved | 63 | Grade C · RCT, 2003 | Adults with type 2 diabetes and low serum magnesium on glibenclamide (Mexico) |
| C-reactive protein in prediabetes with low magnesium | Improved | 62 | Grade C · RCT, 2014 | Adults aged 18 to 65 with new prediabetes and low serum magnesium (Mexico) |
| Depressive symptoms after COVID-19 in adults with low magnesium and vitamin D | Improved | 60 | Grade D · RCT, 2024 | Adults with long-COVID, low serum magnesium, vitamin D deficiency and mild-to-moderate depressive symptoms (Mexico) |
| Insulin resistance and blood pressure in metabolically obese, normal-weight adults | Improved | 47 | Grade C · RCT, 2014 | Normal-weight adults with metabolic abnormalities and low serum magnesium (Mexico) |
| Quality of life in fibromyalgia with topical magnesium chloride spray | Improved | 40 | Grade D · Open-label trial, 2015 | Women with fibromyalgia at a US tertiary centre |
| Depression in older adults with type 2 diabetes and low magnesium | Improved | 23 | Grade D · RCT, 2008 | Older adults with type 2 diabetes, low serum magnesium and new depression (Mexico) |
| Heart rhythm in congestive heart failure | Improved | 21 | Grade D · Crossover RCT, 1993 | Adults with stable heart failure from coronary disease |
| Cycling performance in regular exercisers | Worsened | 15 | Grade D · Crossover RCT, 2025 | Healthy men and women who exercise regularly, without low magnesium (US) |
Every graded row
12 rowsShowing 12 of 12 outcomes. Human trials only.
CGrade CMetabolic syndrome and its components in adults with low magnesiumMetabolic syndrome · tested chlorideMetS 48% vs 77.5% placeboRCT
n 198 · 2018
Improved Metabolic syndrome persisted in 48% vs 77.5% on placebo (P = 0.01). Systolic (−3.6 mm Hg) and diastolic (−5.5 mm Hg) pressure, fasting glucose (−12.4 mg/dL) and triglycerides (−61.2 mg/dL) fell more than with placebo.
- Design
- RCT, n = 198, 2018
- Population
- Adults with metabolic syndrome and low serum magnesium (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 30 ml of 5% magnesium chloride solution daily (382 mg magnesium)
- Duration
- 16 weeks
- Source
- Reference 14 · PubMed 29793665 (opens PubMed)
CGrade CMild-to-moderate depression and anxiety symptomsMood · tested chloridePHQ-9 -6.0 points vs control periodCrossover RCT
n 126 · 2017
Improved Net improvement of 6.0 points on PHQ-9 and 4.5 points on GAD-7 versus the no-treatment period; 112 participants gave analysable data.
- Design
- Crossover RCT, n = 126, 2017
- Population
- Adults in US primary care with PHQ-9 scores of 5 to 19 (mean age 52)
- Form
- Over-the-counter magnesium chloride
- Dose
- 248 mg elemental magnesium/day
- Duration
- 6 weeks active vs 6 weeks no treatment (crossover)
- Source
- Reference 3 · PubMed 28654669 (opens PubMed)
CGrade CFasting glucose in prediabetes with low magnesiumBlood glucose · tested chlorideFasting glucose 86.9 vs 98.3 mg/dLRCT
n 116 · 2015
Improved Versus placebo: fasting glucose 86.9 vs 98.3 mg/dL, HOMA-IR 2.85 vs 4.1 and triglycerides 166.4 vs 227.0 mg/dL; serum magnesium 1.96 vs 1.60 mg/dL.
- Design
- RCT, n = 116, 2015
- Population
- Adults aged 30 to 65 with new prediabetes and low serum magnesium (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 30 ml of 5% magnesium chloride solution daily (382 mg magnesium)
- Duration
- 4 months
- Source
- Reference 5 · PubMed 25937055 (opens PubMed)
CGrade CBlood pressure in people with diabetes, high blood pressure and low magnesiumBlood pressure · tested chlorideSystolic -20.4 vs -4.7 mm HgRCT
n 82 · 2009
Improved Systolic pressure fell 20.4 vs 4.7 mm Hg and diastolic 8.7 vs 1.2 mm Hg, magnesium vs placebo; HDL rose slightly. 79 of 82 completed.
- Design
- RCT, n = 82, 2009
- Population
- Adults aged 40 to 75 with type 2 diabetes and hypertension on captopril, with low serum magnesium (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 2.5 g magnesium chloride daily (50 ml of 5% solution), stated as 450 mg elemental magnesium
- Duration
- 4 months
- Source
- Reference 8 · PubMed 19020533 (opens PubMed)
CGrade CInsulin resistance and HbA1c in type 2 diabetes with low magnesiumBlood glucose · tested chlorideHbA1c 8.0% vs 10.1% placeboRCT
n 63 · 2003
Improved Versus placebo: serum magnesium 0.74 vs 0.65 mmol/l, HOMA-IR 3.8 vs 5.0, fasting glucose 8.0 vs 10.3 mmol/l and HbA1c 8.0% vs 10.1%.
- Design
- RCT, n = 63, 2003
- Population
- Adults with type 2 diabetes and low serum magnesium on glibenclamide (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 50 ml of 5% magnesium chloride solution daily (2.5 g MgCl2; ODS describes it as 300 mg elemental magnesium)
- Duration
- 16 weeks
- Source
- Reference 4 · PubMed 12663588 (opens PubMed)
CGrade CC-reactive protein in prediabetes with low magnesiumInflammation marker · tested chloridehsCRP 4.8 vs 17.1 nmol/LRCT
n 62 · 2014
Improved hsCRP 4.8 vs 17.1 nmol/L and serum magnesium 0.86 vs 0.69 mmol/L at the end of follow-up, magnesium vs control.
- Design
- RCT, n = 62, 2014
- Population
- Adults aged 18 to 65 with new prediabetes and low serum magnesium (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 30 ml of 5% magnesium chloride solution daily
- Duration
- 3 months
- Source
- Reference 6 · PubMed 24814039 (opens PubMed)
CGrade CInsulin resistance and blood pressure in metabolically obese, normal-weight adultsInsulin resistance · tested chlorideHOMA-IR -46.5% vs -5.4%RCT
n 47 · 2014
Improved Changes versus placebo: HOMA-IR -46.5% vs -5.4%, fasting glucose -12.3% vs -1.8%, triglycerides -47.4% vs +10.1%; systolic and diastolic pressure also fell more.
- Design
- RCT, n = 47, 2014
- Population
- Normal-weight adults with metabolic abnormalities and low serum magnesium (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 30 ml of 5% magnesium chloride solution daily (382 mg magnesium)
- Duration
- 4 months
- Source
- Reference 7 · PubMed 24830937 (opens PubMed)
DGrade DDepressive symptoms after COVID-19 in adults with low magnesium and vitamin DMood · tested chlorideBDI <11: 73% vs 34.5%RCT
n 60 · 2024
Improved 73% vs 34.5% reached a Beck Depression Inventory score under 11 (p = 0.006). Mild adverse events in 20% vs 10%.
- Design
- RCT, n = 60, 2024
- Population
- Adults with long-COVID, low serum magnesium, vitamin D deficiency and mild-to-moderate depressive symptoms (Mexico)
- Form
- Magnesium chloride plus vitamin D (control: vitamin D alone)
- Dose
- 1,300 mg/day magnesium chloride (salt weight as reported) with 4,000 IU vitamin D
- Duration
- 4 months
- Source
- Reference 16 · PubMed 39846976 (opens PubMed)
DGrade DQuality of life in fibromyalgia with topical magnesium chloride sprayTopical use · tested chlorideFIQR total improved (P=0.001)Open-label trial
n 40 · 2015
Improved Revised Fibromyalgia Impact Questionnaire scores improved at weeks 2 and 4; only 24 of 40 completed.
- Design
- Open-label trial, n = 40, 2015
- Population
- Women with fibromyalgia at a US tertiary centre
- Form
- Transdermal magnesium chloride spray
- Dose
- 4 sprays per limb twice daily
- Duration
- 4 weeks
- Source
- Reference 10 · PubMed 26343101 (opens PubMed)
DGrade DDepression in older adults with type 2 diabetes and low magnesiumMood · tested chlorideSimilar to imipramine 50 mgRCT
n 23 · 2008
Improved Depression scores improved similarly with magnesium chloride and with imipramine 50 mg (11.4 vs 10.9 points at the end, no significant difference).
- Design
- RCT, n = 23, 2008
- Population
- Older adults with type 2 diabetes, low serum magnesium and new depression (Mexico)
- Form
- Magnesium chloride solution
- Dose
- 50 ml of 5% magnesium chloride solution daily (450 mg elemental magnesium)
- Duration
- 12 weeks
- Source
- Reference 9 · PubMed 19271419 (opens PubMed)
DGrade DHeart rhythm in congestive heart failureHeart rhythm · tested chlorideCouplets -52% vs placeboCrossover RCT
n 21 · 1993
Improved Versus placebo, single premature ventricular beats fell 23%, couplets 52% and non-sustained ventricular tachycardia episodes 24%; serum magnesium and potassium rose.
- Design
- Crossover RCT, n = 21, 1993
- Population
- Adults with stable heart failure from coronary disease
- Form
- Enteric-coated magnesium chloride
- Dose
- 15.8 mmol magnesium per day
- Duration
- 6 weeks per arm
- Source
- Reference 11 · PubMed 8237806 (opens PubMed)
DGrade DCycling performance in regular exercisersExercise performance · tested chlorideVO2max 41.3 vs 44.4 mL/kg/minCrossover RCT
n 15 · 2025
Worsened Versus placebo, VO2max was lower (41.3 vs 44.4 mL/kg/min) and 30-second sprint power fell (415 vs 439 W); the 10 km time trial and gut microbiota did not change.
- Design
- Crossover RCT, n = 15, 2025
- Population
- Healthy men and women who exercise regularly, without low magnesium (US)
- Form
- Magnesium chloride liquid (ReMag)
- Dose
- 300 mg of magnesium chloride twice daily (salt weight as reported; elemental magnesium not stated)
- Duration
- 9 days per phase, 3-week washout
- Source
- Reference 15 · PubMed 40077784 (opens PubMed)
What the numbers add up to
Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.
Benefits were in people with low magnesium
Topical claims outrun the data
Studied doses
Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.
Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.
Doses studied in human trials
NIH ODS updated Jan 6, 2026Doses studied in human trials ranged from 248 mg/day of elemental magnesium as over-the-counter magnesium chloride for 6 weeks to 2.5 g/day of magnesium chloride solution (stated as up to 450 mg elemental magnesium) for 4 months; a 9-day exercise trial used 300 mg of magnesium chloride twice daily (elemental amount not stated). Several trial doses exceed the 350 mg/day upper limit for supplemental magnesium.13481415
Intake reference: Supplemental magnesium, chloride included, tops out at 350 mg/day for adults; the RDA from all sources is 310–420 mg/day.1 The cap ignores magnesium in food. NIH ODS fact sheet (updated January 6, 2026).
Interactions and safety
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
What Magnesium chloride meets
7 cited rowsMedicines 6
Supplements and foods 1
- Measured in a human study
- Reference summary
Choose a medicine or supplement above to read its cited rows here.
Also cited:
Levothyroxine
PK studyMeasured in a human study
Levothyroxine, for example thyroid hormone tablets (Euthyrox was the brand tested): In a crossover study of 15 healthy adults, a 1 mg dose of levothyroxine given together with 243–301 mg of magnesium cut thyroxine absorption by 12% with magnesium aspartate and by 7% (not significant) with magnesium citrate. The authors advise spacing levothyroxine apart from magnesium products. Chloride itself was not tested.
Source 17, Clin Transl Sci (2025)
Loop and thiazide diuretics
NIH fact sheetReference summaryCan lower levels
Loop and thiazide diuretics, for example furosemide, hydrochlorothiazide: Long-term use can increase urinary magnesium loss.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
Oral bisphosphonates
NIH fact sheetReference summary
Oral bisphosphonates, for example alendronate (Fosamax): Magnesium can reduce bisphosphonate absorption; separate them by at least 2 hours.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
Potassium-sparing diuretics
NIH fact sheetReference summary
Potassium-sparing diuretics, for example amiloride, spironolactone: They reduce magnesium excretion.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
Proton pump inhibitors (long-term)
NIH fact sheetReference summaryCan lower levels
Proton pump inhibitors (long-term), for example esomeprazole, lansoprazole: Use for more than about a year can cause low magnesium; in FDA-reviewed cases supplements did not correct it in 25%.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
Tetracycline and quinolone antibiotics
NIH fact sheetReference summary
Tetracycline and quinolone antibiotics, for example doxycycline, ciprofloxacin, levofloxacin: Magnesium forms insoluble complexes with them. ODS: the antibiotic should be taken at least 2 hours before or 4 to 6 hours after magnesium.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
ZincZinc page
NIH fact sheetReference summary
High-dose zinc, for example 142 mg/day zinc from supplements: NIH ODS cites a study in which very high zinc intake interfered with magnesium absorption and balance.
Source 1, NIH Office of Dietary Supplements (ODS) (2026)
Interactions
7 agents| Agent | What the source says | Evidence |
|---|---|---|
| Medicines4 | ||
| Oral bisphosphonatese.g. alendronate (Fosamax) | Magnesium can reduce bisphosphonate absorption; separate them by at least 2 hours.1 | NIH fact sheet |
| Tetracycline and quinolone antibioticse.g. doxycycline, ciprofloxacin, levofloxacin | Magnesium forms insoluble complexes with them. ODS: the antibiotic should be taken at least 2 hours before or 4 to 6 hours after magnesium.1 | NIH fact sheet |
| Potassium-sparing diureticse.g. amiloride, spironolactone | They reduce magnesium excretion.1 | NIH fact sheet |
| Levothyroxinee.g. thyroid hormone tablets (Euthyrox was the brand tested) | In a crossover study of 15 healthy adults, a 1 mg dose of levothyroxine given together with 243–301 mg of magnesium cut thyroxine absorption by 12% with magnesium aspartate and by 7% (not significant) with magnesium citrate. The authors advise spacing levothyroxine apart from magnesium products. Chloride itself was not tested.17 | PK study |
| Medicines that can lower levels2 | ||
| Loop and thiazide diureticse.g. furosemide, hydrochlorothiazide | Long-term use can increase urinary magnesium loss.1 | NIH fact sheet |
| Proton pump inhibitors (long-term)e.g. esomeprazole, lansoprazole | Use for more than about a year can cause low magnesium; in FDA-reviewed cases supplements did not correct it in 25%.1 | NIH fact sheet |
| Other supplements1 | ||
| High-dose zince.g. 142 mg/day zinc from supplements | NIH ODS cites a study in which very high zinc intake interfered with magnesium absorption and balance.1 | NIH fact sheet |
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between Magnesium chloride and your picks, and between your picks.
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Add a supplement or medicine you take to check it against Magnesium chloride.
Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.
Who should be careful
4 groups- Kidney problems
- ODS: the risk of magnesium toxicity rises with impaired kidney function because excess magnesium cannot be cleared.1
- High intakes and digestive effects
- Diarrhea, nausea and cramping are the usual first signs of too much; very large intakes from laxatives and antacids (over about 5,000 mg/day) have caused toxicity.1
- Pregnancy and breastfeeding
- ODS sets the same 350 mg/day upper limit for supplemental magnesium in pregnancy and lactation; the RDA from all sources is 350–400 mg in pregnancy and 310–360 mg in lactation.1
- Children
- Upper limits for supplemental magnesium are 65 mg/day at ages 1 to 3 and 110 mg/day at ages 4 to 8.1
How to read the label
What to check on the Supplement Facts panel.
How to read the label
4 checksElemental vs salt weight
Magnesium oil
Sprays sold as 'magnesium oil' are concentrated magnesium chloride solutions; a 2017 review found no good evidence that magnesium is absorbed through the skin in useful amounts.12
Liquid concentrates: check the strength
Add up every magnesium source
The 350 mg/day adult limit counts magnesium from all supplements and medicines combined, including multivitamins, antacids and laxatives, but not food.1
Where to buy Magnesium chloride
Products from brands we partner with that contain Magnesium chloride. Check the amount per serving against the doses studied above, and the label for other ingredients.
Magnesium chloride products from partner brands
1 product Paid links · we earn a commission- Quick pickHerbsProNutricost Magnesium Chloride powder, unflavoured, 2 lb
1 scoop (1.9 g): 210 mg magnesium from 1,900 mg magnesium chloride hexahydrate (label)
$24.95one-timeChecked Oct 15, 2026
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
8 answersDoes magnesium chloride lower blood sugar?
Does magnesium oil spray work?
Does magnesium chloride help with depression?
Small trials suggest it may in some groups: an open-label US crossover found better depression scores over 6 weeks, a Mexican trial in older adults with diabetes found results similar to imipramine, and an open-label trial after COVID-19 found benefit with vitamin D. None used a placebo, so expectation effects cannot be excluded.3916
Does magnesium chloride improve exercise performance?
One small trial says no. In a 2025 double-blind crossover, 9 days of magnesium chloride slightly lowered VO2max and sprint power in 15 regular exercisers without low magnesium, and did not change a 10 km time trial.15
What are the side effects?
Diarrhea, nausea and cramping at high doses; ODS lists chloride among the forms most often reported to cause diarrhea. The adult upper limit for supplemental magnesium is 350 mg/day.1
How much magnesium is in magnesium chloride?
Is magnesium chloride safe in pregnancy and breastfeeding?
No chloride-specific data are in our sources. NIH ODS sets the same 350 mg/day upper limit for supplemental magnesium in pregnancy and lactation as for other adults; RDAs from all sources are 350–400 mg/day in pregnancy and 310–360 mg/day while breastfeeding.1
Is magnesium chloride well absorbed?
ODS says small studies find magnesium chloride, citrate, aspartate and lactate are absorbed more completely than magnesium oxide or sulfate.1
Sources
17 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
17 sources- 1Magnesium: Fact Sheet for Health Professionals (updated January 6, 2026)Fact sheet NIH Office of Dietary Supplements (ODS), 2026 · ods.od.nih.gov
- 2Magnesium chloride hexahydrate (CID 24644): Cl2H12MgO6, MW 203.30Database PubChem, National Library of Medicine, 2026 · pubchem.ncbi.nlm.nih.gov
- 3Role of magnesium supplementation in the treatment of depression: A randomized clinical trial.Crossover RCT PLoS One, 2017 · PMID 28654669
- 4Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial.RCT Diabetes Care, 2003 · PMID 12663588
- 5Oral magnesium supplementation improves glycaemic status in subjects with prediabetes and hypomagnesaemia: A double-blind placebo-controlled randomized trial.RCT Diabetes Metab, 2015 · PMID 25937055
- 6Oral magnesium supplementation decreases C-reactive protein levels in subjects with prediabetes and hypomagnesemia: a clinical randomized double-blind placebo-controlled trial.RCT Arch Med Res, 2014 · PMID 24814039
- 7Oral magnesium supplementation improves the metabolic profile of metabolically obese, normal-weight individuals: a randomized double-blind placebo-controlled trial.RCT Arch Med Res, 2014 · PMID 24830937
- 8The effect of lowering blood pressure by magnesium supplementation in diabetic hypertensive adults with low serum magnesium levels: a randomized, double-blind, placebo-controlled clinical trial.RCT J Hum Hypertens, 2009 · PMID 19020533
- 9Efficacy and safety of oral magnesium supplementation in the treatment of depression in the elderly with type 2 diabetes: a randomized, equivalent trial.RCT Magnes Res, 2008 · PMID 19271419
- 10Effects of transdermal magnesium chloride on quality of life for patients with fibromyalgia: a feasibility study.Open-label trial J Integr Med, 2015 · PMID 26343101
- 11Effects of long-term oral magnesium chloride replacement in congestive heart failure secondary to coronary artery disease.Crossover RCT Am J Cardiol, 1993 · PMID 8237806
- 12Myth or Reality-Transdermal Magnesium?Review Nutrients, 2017 · PMID 28788060
- 13Magnesium chloride (CID 5360315): Cl2Mg, MW 95.21Database PubChem, National Library of Medicine, 2026 · pubchem.ncbi.nlm.nih.gov
- 14Oral Magnesium Supplementation and Metabolic Syndrome: A Randomized Double-Blind Placebo-Controlled Clinical Trial.RCT Adv Chronic Kidney Dis, 2018 · PMID 29793665
- 15Short-Term Magnesium Supplementation Has Modest Detrimental Effects on Cycle Ergometer Exercise Performance and Skeletal Muscle Mitochondria and Negligible Effects on the Gut Microbiota: A Randomized Crossover Clinical Trial.Crossover RCT Nutrients, 2025 · PMID 40077784
- 16Combined oral supplementation with magnesium plus vitamin D alleviates mild to moderate depressive symptoms related to long-COVID: an open-label randomized, controlled clinical trial.RCT Magnes Res, 2024 · PMID 39846976
- 17Single Center, Open-Label, Randomized Crossover Trial on Drug-Drug Interactions of Levothyroxine/Magnesium-Citrate and Levothyroxine/Magnesium-Aspartate in Healthy Subjects-The ThyroMag Trial.PK study Clin Transl Sci, 2025 · PMID 41221788
What changed
Every dated change to this page: what changed, who made it and why.
Change log
4 entries| Date | Change | Who and why |
|---|---|---|
| definition, summary, key facts, evidence, doses, interactions, label guide, FAQ | Added three evidence rows: 2018 RCT in metabolic syndrome with low magnesium (PMID 29793665, n=198, grade C), 2024 open-label RCT of magnesium chloride plus vitamin D for post-COVID depressive symptoms (PMID 39846976, grade D) and a 2025 sponsor-funded crossover RCT showing slightly worse cycling performance (PMID 40077784, grade D); levothyroxine (PMID 41221788) and high-dose zinc (NIH ODS) interactions; two label-guide steps (liquid strength; adding up every source); definition trimmed to 140 characters and three FAQs. Pregnancy/lactation, upper limit and interactions re-checked against the NIH ODS magnesium fact sheet (updated January 6, 2026). Fact-checked against the sources; corrected: the exercise result is now described as one small trial, and its 300 mg dose is marked as magnesium chloride salt weight (PMID 40077784). | Writer: Kymata Health EditorialTrigger: A–Z page audit |
| Related | Added a link to the Bella Bleu Naturals spotlight, whose DMSO balms, gel and roll-on list magnesium chloride for use on the skin. | Writer: Kymata Health EditorialTrigger: New related page |
| Evidence | Corrected the study design on: Mild-to-moderate depression and anxiety symptoms. Each participant had 6 weeks of magnesium and 6 weeks without treatment in random order, so the trial is a crossover, not a parallel-group trial. | Writer: Kymata Health EditorialTrigger: Correction |
| all | Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal; none retracted) and each cited abstract read; numbers taken from the abstracts, with ODS used for the elemental dose of the 2003 trial. Funding disclosed: University of Vermont Tufo fund (depression trial, full text); the Mexican trials are from the IMSS Durango unit with funding not stated; one transdermal review author lists a Protina e-mail address (abstract affiliations). Safety, intake limits and interactions from the ODS magnesium fact sheet (updated 2026-01-06). Where to buy: Nutricost Magnesium Chloride powder (label checked 2026-10-15). | Writer: Kymata Health EditorialTrigger: new page |
Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.