Magnesium and Potassium Together: Is It Safe?

Yes, healthy adults can take magnesium and potassium together at food-level amounts or standard supplement doses. A 32-week trial gave 60 mmol of potassium and 20 mmol of magnesium a day to 37 adults with mild hypertension and found it well tolerated¹. Take care if your kidneys or medicines (ACE inhibitors, ARBs, potassium-sparing diuretics) hold on to potassium, or if you use very large amounts of potassium supplements or salt substitutes².

The pair works together in the body, but the one trial that compared potassium alone with potassium plus magnesium found no added benefit from the magnesium¹. Where the pairing matters is low levels: low magnesium makes the body waste potassium³.

Magnesium keeps potassium in the body. When magnesium inside kidney cells falls, the brake on potassium channels (ROMK) in the distal tubule is released, and the kidney pours more potassium into the urine³. That is why low magnesium makes low potassium "refractory" to potassium treatment^{3, 4}.

Low magnesium alone does not always cause low potassium. Extra sodium reaching the distal tubule, or high aldosterone, may also be needed³.

The overlap is common:

• 38% to 42%: share of potassium-depleted patients who also had magnesium deficiency in a 1992 review⁴.
• 42%: share of patients with low potassium who had low magnesium in a 1987 review⁵.
• More than 50%: NIH's estimate of people with clinically significant low potassium who might also lack magnesium. When both are low, NIH says both should be treated together².
• r = 0.27: correlation between serum magnesium and potassium in a records review of 103 coronary care admissions. It is a weak link, and mild lows did not predict arrhythmias there⁶.

A blood magnesium test can miss the problem, because deficiency is not always visible in serum. A 1987 review therefore advised repleting both minerals in patients with low potassium⁷.

Does magnesium raise potassium levels?

Not when magnesium is already normal. In 39 untreated hypertensive adults with normal magnesium turnover, 15 mmol of magnesium a day for two months changed neither serum nor muscle potassium⁸.

With a diuretic on board the picture changes. In 11 hypertensive adults taking hydrochlorothiazide 50 mg a day, potassium chloride 1 g twice daily plus magnesium hydroxide 500 mg twice daily raised serum potassium (P < 0.01), and potassium chloride alone did not⁹.

A trial of 22 healthy volunteers on hydrochlorothiazide 50 mg a day for six months compared potassium-magnesium-citrate with potassium chloride. Serum magnesium rose about 10% on the combination and did not rise on potassium chloride, though serum electrolytes stayed normal in both groups¹⁰.

For most healthy adults, yes, at food-level amounts and standard supplement doses. These figures are for adults. The numbers to know:

• Magnesium target: 310 to 420 mg a day for adults, depending on age and sex¹¹.
• Magnesium upper limit: 350 mg a day from supplements and medicines. Food does not count toward it¹¹.
• Magnesium side effect: high supplement doses commonly cause diarrhea, nausea and cramping¹¹.
• Potassium target: 2,600 mg a day for women and 3,400 mg for men aged 19 and over².
• Potassium pills: most potassium-only supplements hold up to 99 mg, because higher-dose potassium chloride products have been linked to small-bowel lesions².
• Salt substitutes: 440 to 2,800 mg of potassium per teaspoon².

Trials used far more potassium than a supplement shelf offers. The 32-week trial gave 60 mmol a day, which equals 2,346 mg^{1, 2}. A 232-patient trial gave 6 mmol of magnesium and 12 mmol of potassium daily as aspartate for 3 weeks¹². Doses like these belong under a clinician's guidance.

In healthy people with normal kidney function, extra potassium or magnesium from food is not a health risk, because the kidneys remove the excess^{2, 11}.

Probably not, and the evidence is thin. Two trials and one pooled review tested the pair directly:

• 37 adults, 32 weeks: potassium 60 mmol a day alone or with magnesium 20 mmol a day lowered systolic and diastolic pressure (p < 0.001). Magnesium added nothing¹.
• 125 adults, 6 months: adults with untreated mild or borderline hypertension were split across four regimens, with no potassium-only arm. The arm taking potassium 60 mmol plus magnesium 15 mmol (360 mg) a day changed systolic pressure by -1.3 mmHg (95% CI -4.4 to +1.8) against placebo, a non-significant result. Usual diets already held about 77 mmol of potassium a day¹³.
• Cochrane pooling of 3 trials, 277 adults: potassium plus magnesium cut systolic pressure by 4.6 mmHg (95% CI -9.9 to 0.7), which was not significant. Heterogeneity was high (I² = 68%) and trial quality was poorly reported. One sensitivity analysis using alternative data reached significance (-5.8 mmHg, 95% CI -10.5 to -1.0)¹⁴.

Each mineral has its own pooled evidence. A 2025 meta-analysis of 38 trials in 2,709 people found that magnesium lowered systolic pressure by 2.81 mmHg and diastolic by 2.05 mmHg, with bigger drops in people on blood pressure drugs (-7.68 mmHg) and those with low magnesium (-5.97 mmHg)¹⁵.

A dose-response analysis of 32 trials found a U-shaped curve for potassium. Beyond a 30 mmol/day rise in urinary potassium excretion between supplement and control arms, the benefit weakened. Above a rise of about 80 mmol/day, blood pressure went up, a rise seen in people on antihypertensive drugs but not in untreated people. The authors urge caution because few trials tested high intakes¹⁶.

In people with normal blood pressure, a 2024 analysis found lower doses and longer treatment gave larger reductions in systolic pressure. Magnesium at 360 mg a day or less lowered it by 3.03 mmHg, and treatment longer than 3 months by 4.31 mmHg. Potassium at 60 mmol a day or less lowered it by 2.34 mmHg, and treatment longer than a month by 2.80 mmHg. The authors call for validation¹⁷.

For the single-nutrient detail, see magnesium for blood pressure regulation and potassium for high blood pressure.

Modestly, in people who already have frequent extra beats. In the MAGICA trial, 232 patients with more than 720 ventricular premature beats a day took 6 mmol of magnesium and 12 mmol of potassium as aspartate, or placebo, for 3 weeks. Beats fell by a median of 17.4% on treatment (p = 0.001 against the run-in baseline) against 7.4% on placebo, which is 2.4 times greater suppression. A predefined 60% suppression was reached by 25% on treatment versus 15% on placebo (p = 0.044). Repetitive and supraventricular arrhythmias, and symptoms, did not change¹².

Adding magnesium to potassium did not beat potassium alone in the thiazide trial above. Both supplements showed a trend toward fewer ventricular extra beats, with no difference between them⁹.

Low levels still matter. Both deficiencies are associated with more ventricular ectopy and may raise the risk of sudden death⁷. Rhythm symptoms deserve a proper work-up, not a supplement guess. See magnesium for arrhythmia and palpitations.

What about potassium magnesium aspartate?

Aspartate is the salt form used in the MAGICA trial. In a small physiology study, seven trained men took 7.2 g of potassium-magnesium aspartate over 24 hours. Their heart rate, oxygen use and blood chemistry during 90 minutes of treadmill walking did not differ from placebo¹⁸.

Nothing is banned outright, but some pairings need care: do not add potassium on top of an ACE inhibitor, an ARB or a potassium-sparing diuretic without medical advice, and keep magnesium away from certain drugs. Several common drugs move one or both minerals, and the direction differs:

• Thiazide diuretics: increase urinary potassium loss and can cause low potassium². In 9,820 Rotterdam Study participants, thiazide use was associated with 3.14-fold higher odds of low magnesium (under 1 daily dose) and 2.74-fold (1 dose or more). This was a cross-sectional analysis, so it shows an association¹⁹.
• Loop diuretics: increase potassium loss², and chronic use can deplete magnesium¹¹. The Rotterdam data disagreed: loop users had slightly higher serum magnesium¹⁹.
• Potassium-sparing diuretics (amiloride, spironolactone): raise potassium and reduce magnesium excretion^{2, 11}. Thiazide users who also took one were not more likely to have low magnesium¹⁹.
• ACE inhibitors and ARBs: reduce urinary potassium excretion and can cause high potassium. NIH advises monitoring².
• Proton pump inhibitors: can cause low magnesium when taken for prolonged periods, typically more than a year¹¹.
• Oral bisphosphonates, tetracyclines, quinolone antibiotics: magnesium can interfere with them. Take magnesium at least 2 hours before or after a bisphosphonate¹¹.

Not every expert agrees that diuretics drain magnesium. A 1993 review found that controlled trials do not show it for conventional thiazide doses, so most people on those doses do not need magnesium supplements²⁰.

That makes a blood test the sensible first step, not a supplement. Our guides on what not to take with magnesium and blood pressure medicines and supplements cover more interactions.

The group above is the main one. More cautions apply:

• Kidney disease and potassium: when the kidneys cannot clear potassium, even food can push levels up². See chronic kidney disease for the kidney-specific picture.
• Kidney disease and magnesium: the risk of magnesium toxicity increases with impaired kidney function or kidney failure, because the ability to remove excess magnesium is reduced or lost¹¹. Check with a clinician before taking magnesium supplements, laxatives or antacids.
• Large magnesium doses: toxicity has been reported mainly with laxatives and antacids providing more than 5,000 mg a day, and it can cause low blood pressure, vomiting and an irregular heartbeat¹¹.
• Large potassium doses: very high amounts of potassium supplements or potassium salt substitutes can exceed the kidneys' capacity and cause acute hyperkalemia even in healthy people².
• Children: the 350 mg magnesium limit applies from age 9. It is 65 mg at 1 to 3 years and 110 mg at 4 to 8 years, and a fatal case of magnesium toxicity has been reported in a 28-month-old¹¹. Do not give young children these supplements without medical advice.

Mild low potassium (under about 3.6 mmol/L) causes constipation, fatigue, muscle weakness and malaise. Moderate to severe cases (under about 2.5 mmol/L) can cause large volumes of dilute urine, muscle paralysis, poor breathing and arrhythmias, especially with heart disease².

Early signs of low magnesium are loss of appetite, nausea, vomiting, fatigue and weakness. As deficiency worsens, numbness, tingling, cramps, seizures, personality changes and abnormal heart rhythms can occur¹¹.

Those signs are non-specific, so a blood test confirms the diagnosis. Normal serum potassium is about 3.6 to 5.0 mmol/L², and normal serum magnesium is 0.75 to 0.95 mmol/L¹¹. Low potassium is rare in healthy people with normal kidneys, but affects up to 21% of hospitalized patients, usually because of diuretics and other drugs².

What causes low potassium and low magnesium?

Potassium falls from diarrhea, vomiting, diuretics, large laxative doses, heavy sweating, inflammatory bowel disease and refeeding after starvation. Low intake alone rarely causes it². Magnesium falls with Crohn's disease and celiac disease, type 2 diabetes, alcohol dependence, older age and long-term proton pump inhibitor use¹¹.

There is no safe do-it-yourself shortcut to raise potassium. True low potassium is treated by a clinician who fixes the cause and checks magnesium too, since NIH advises treating both at once when both are low². Undiagnosed low magnesium is the classic reason potassium refuses to rise⁴.

Food is the simplest way to get both. These foods carry useful amounts of each, per the NIH fact sheets:

• Cashews, 1 ounce: 74 mg magnesium, 187 mg potassium^{11, 2}.
• Soymilk, 1 cup: 61 mg magnesium, 287 mg potassium^{11, 2}.
• Banana, 1 medium: 32 mg magnesium, 422 mg potassium^{11, 2}.
• Salmon, 3 ounces cooked: 26 mg magnesium, 326 mg potassium^{11, 2}.
• Raisins, ½ cup: 23 mg magnesium, 618 mg potassium^{11, 2}.
• Broccoli, ½ cup cooked: 12 mg magnesium, 229 mg potassium^{11, 2}.

Beans, lentils, leafy greens, nuts and seeds lead their own lists. See our guides to magnesium-rich foods and potassium-rich foods for the full rankings.

Common potassium sources include dried apricots (755 mg per ½ cup), cooked lentils (731 mg per cup), a baked potato (610 mg) and canned kidney beans (607 mg per cup)².

The DASH eating pattern emphasizes potassium from fruits, vegetables and low-fat dairy and provides about three times the potassium of the average American diet. It lowers systolic pressure by 5.5 mmHg and diastolic by 3.0 mmHg on average. It also raises magnesium and calcium, so potassium's own share cannot be separated².

Orange juice supplies 496 mg of potassium per cup². About 48% of Americans take in less magnesium from food and drink than their estimated average requirement¹¹.

Use this decision rule:

1. Start with food if you are a healthy adult. The foods above cover both. The last two steps apply first if you have kidney disease or take the drugs named in them.
2. On a diuretic or a proton pump inhibitor? Ask for a blood test of potassium and magnesium before adding either.
3. On an ACE inhibitor, an ARB, a potassium-sparing diuretic, or with kidney disease? Do not add potassium without a clinician.
4. Taking magnesium? Stay under the 350 mg supplemental limit and space it 2 hours from an oral bisphosphonate¹¹.

We found no trial that compared times of day for taking the two together. Timing follows your other medicines and your gut tolerance. For magnesium on its own, see when to take magnesium.

The electrolytes page covers sodium alongside both.

Related conditions

• Magnesium Deficiency
• Potassium Deficiency
• Arrhythmia
• Elevated Blood Pressure
• Chronic Kidney Disease

We searched PubMed through a research-paper index across five framings: magnesium-potassium interaction, magnesium and blood pressure, potassium and blood pressure, potassium-magnesium aspartate, and diuretic-related deficiency. We read the PubMed abstracts of 18 records and the NIH Office of Dietary Supplements fact sheets for magnesium and potassium, all on 1 November 2026. All 20 sources are cited above.

We prioritised trials and systematic reviews in adults. Several key trials of the pair are decades old and small, and none tested hard outcomes such as heart attack or death. The evidence for any benefit of the pair over potassium alone is limited. This article is not medical advice.

1. Patki PS, et al. Efficacy of potassium and magnesium in essential hypertension: a double-blind, placebo controlled, crossover study. BMJ. 1990;301(6751):521-3. doi:10.1136/bmj.301.6751.521
2. National Institutes of Health, Office of Dietary Supplements. Potassium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/
3. Huang CL, et al. Mechanism of hypokalemia in magnesium deficiency. J Am Soc Nephrol. 2007;18(10):2649-52. doi:10.1681/ASN.2007070792 Our study summary.
4. Whang R, et al. Refractory potassium repletion. A consequence of magnesium deficiency. Arch Intern Med. 1992;152(1):40-5. https://pubmed.ncbi.nlm.nih.gov/1728927/ Our study summary.
5. Dyckner T, et al. Potassium/magnesium depletion in patients with cardiovascular disease. Am J Med. 1987;82(3A):11-7. doi:10.1016/0002-9343(87)90127-6
6. Boyd JC, et al. Relationship of potassium and magnesium concentrations in serum to cardiac arrhythmias. Clin Chem. 1984;30(5):754-7. https://pubmed.ncbi.nlm.nih.gov/6713638/
7. Whang R. Magnesium deficiency: pathogenesis, prevalence, and clinical implications. Am J Med. 1987;82(3A):24-9. doi:10.1016/0002-9343(87)90129-x
8. Plum-Wirell M, et al. Nutritional magnesium supplementation does not change blood pressure nor serum or muscle potassium and magnesium in untreated hypertension. A double-blind crossover study. Magnes Res. 1994;7(3-4):277-83. https://pubmed.ncbi.nlm.nih.gov/7786691/
9. Lumme JA, et al. The effect of potassium and potassium plus magnesium supplementation on ventricular extrasystoles in mild hypertensives treated with hydrochlorothiazide. Int J Cardiol. 1989;25(1):93-7. doi:10.1016/0167-5273(89)90168-x
10. Odvina CV, et al. Prevention of thiazide-induced hypokalemia without magnesium depletion by potassium-magnesium-citrate. Am J Ther. 2006;13(2):101-8. doi:10.1097/01.mjt.0000149922.16098.c0
11. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
12. Zehender M, et al. Antiarrhythmic effects of increasing the daily intake of magnesium and potassium in patients with frequent ventricular arrhythmias. Magnesium in Cardiac Arrhythmias (MAGICA) Investigators. J Am Coll Cardiol. 1997;29(5):1028-34. doi:10.1016/s0735-1097(97)00053-3
13. Sacks FM, et al. Combinations of potassium, calcium, and magnesium supplements in hypertension. Hypertension. 1995;26(6 Pt 1):950-6. doi:10.1161/01.hyp.26.6.950
14. Beyer FR, et al. Combined calcium, magnesium and potassium supplementation for the management of primary hypertension in adults. Cochrane Database Syst Rev. 2006;2006(3):CD004805. doi:10.1002/14651858.CD004805.pub2
15. Argeros Z, et al. Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Hypertension. 2025;82(11):1844-1856. doi:10.1161/HYPERTENSIONAHA.125.25129
16. Filippini T, et al. Potassium Intake and Blood Pressure: A Dose-Response Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 2020;9(12):e015719. doi:10.1161/JAHA.119.015719 Our study summary.
17. Behers BJ, et al. Magnesium and Potassium Supplementation for Systolic Blood Pressure Reduction in the General Normotensive Population: A Systematic Review and Subgroup Meta-Analysis for Optimal Dosage and Treatment Length. Nutrients. 2024;16(21). doi:10.3390/nu16213617
18. Hagan RD, et al. Absence of effect of potassium-magnesium aspartate on physiologic responses to prolonged work in aerobically trained men. Int J Sports Med. 1982;3(3):177-81. doi:10.1055/s-2008-1026085
19. Kieboom BCT, et al. Thiazide but not loop diuretics is associated with hypomagnesaemia in the general population. Pharmacoepidemiol Drug Saf. 2018;27(11):1166-1173. doi:10.1002/pds.4636
20. Davies DL, et al. Do diuretics cause magnesium deficiency?. Br J Clin Pharmacol. 1993;36(1):1-10. doi:10.1111/j.1365-2125.1993.tb05883.x