Most people can take magnesium and potassium together: no NIH or MedlinePlus source describes one blocking the other, and the two minerals actually work as a pair. Severe magnesium deficiency can cause low blood potassium, and NIH notes that more than 50% of people with clinically significant hypokalemia might be low in magnesium, so doctors treat both at once. The caution is about potassium, not the pairing: with chronic kidney disease, ACE inhibitors, ARBs or potassium-sparing diuretics, even dietary potassium below the 2,600 to 3,400 mg Adequate Intake can push blood potassium too high. Over-the-counter potassium pills usually hold no more than 99 mg, about 2% of the Daily Value, because of FDA rules on potassium drugs. Supplemental magnesium has an adult upper limit of 350 mg a day.
This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or qualified healthcare provider before starting any supplement regimen.
Pair checker
Can I take these together?
Usually yes, they can share a dose, but check with a doctor first if you have kidney disease or take ACE inhibitors, ARBs or potassium-sparing diuretics.
Why
No NIH or MedlinePlus source describes either mineral blocking the other, and low magnesium increases potassium loss in urine, so doctors treat both deficiencies together. The risk is potassium itself: kidney disease, ACE inhibitors, ARBs and potassium-sparing diuretics reduce potassium excretion and can cause high blood potassium even from food amounts.
Timing
Take them together with a meal: MedlinePlus advises taking potassium with or right after food and a full glass of water.
Sources
Check your whole list, not just one pair
Supplement Tracker checks every supplement you take against the others and reminds you of each dose at its own time.
Magnesium and potassium often land in the same shopping basket. Both are sold as electrolytes, both turn up in cramp and hydration products, and a blood test that flags one sometimes flags the other. So can you take magnesium and potassium together?
For most people, yes. We found no NIH or MedlinePlus source describing either mineral blocking the other's absorption, and the two are linked in a way that helps rather than hurts. The real question is not the pairing but the potassium itself. If you have kidney disease, or take an ACE inhibitor, an ARB or a potassium-sparing diuretic, extra potassium can build up in the blood, and that is a conversation for your doctor before any supplement.
How They Interact
The NIH magnesium fact sheet describes magnesium as playing "a role in the active transport of calcium and potassium ions across cell membranes," which matters for nerve signals, muscle contraction and a normal heart rhythm. It also notes that in severe cases, magnesium deficiency can cause hypokalemia, meaning low blood potassium.
The NIH potassium fact sheet explains the other side. Magnesium depletion can contribute to hypokalemia by increasing the amount of potassium lost in urine. More than 50% of people with clinically significant hypokalemia might have magnesium deficiency, and in people with both, the fact sheet says the two should be treated at the same time.
The reason is described in a 2007 review by Huang and Kuo in the Journal of the American Society of Nephrology: when magnesium inside kidney cells falls, a brake on the potassium channel ROMK is released, and the kidney secretes more potassium. The authors write that magnesium deficiency makes hypokalemia "refractory to treatment by potassium." In plain terms, potassium given alone may not stick until magnesium is corrected. This applies to people with diagnosed low levels under medical care, not to a healthy person adding a supplement.
What the Research Says
Who runs low. Low potassium is rare in healthy people with normal kidney function, according to NIH. It usually follows diarrhea, vomiting or medicines: loop diuretics such as furosemide and thiazide diuretics increase potassium loss in urine. The magnesium fact sheet says the same loop and thiazide diuretics, taken long term, can increase magnesium loss too. That overlap is one reason the two deficiencies travel together. Our guide to magnesium deficiency symptoms covers who is at risk on the magnesium side.
Why potassium pills are so small. NIH reports that most potassium-only supplements contain up to 99 mg, about 2% of the Daily Value. Manufacturers stay at that level because FDA has ruled that some oral potassium chloride drugs above 99 mg are not safe, having been linked to small-bowel lesions, and requires a warning on some potassium salts above 99 mg per tablet. FDA has not ruled on whether supplements above 99 mg need that warning. The practical effect: NIH notes that supplement users add a mean of only 87 mg a day to their total potassium intake, a small share of the 2,600 mg (women) to 3,400 mg (men) Adequate Intake.
When potassium becomes the risk. NIH did not set an upper limit for potassium, because there is no evidence that high intakes cause hyperkalemia (high blood potassium) in adults with normal kidney function. The exceptions are specific. In people with chronic kidney disease, or who take ACE inhibitors such as benazepril, ARBs such as losartan, or potassium-sparing diuretics such as amiloride and spironolactone, even dietary potassium below the Adequate Intake can cause hyperkalemia. Very large amounts of potassium supplements or potassium salt substitutes could also exceed the kidneys' capacity in healthy people. Salt substitutes vary from about 440 mg to 2,800 mg of potassium per teaspoon, far more than any over-the-counter pill.
Magnesium has its own kidney caution. The magnesium fact sheet notes that the risk of magnesium toxicity rises with impaired kidney function, and that potassium-sparing diuretics reduce magnesium excretion as well. So the same two groups, kidney disease and potassium-sparing diuretics, should check before taking either mineral.
Cramps. NIH lists muscle cramps among the symptoms of magnesium deficiency, and mild hypokalemia brings muscle weakness and fatigue. Neither fact sheet says that potassium supplements prevent everyday cramps, and the evidence on magnesium for ordinary night cramps is weak, as our page on magnesium for leg cramps explains.
Practical Recommendations
- If you are healthy and take no relevant medicine, a standard magnesium supplement and an over-the-counter potassium pill can go in the same dose. There is no documented reason to space them apart.
- Take potassium with food and water. MedlinePlus advises taking prescription potassium with or immediately after meals, with a full glass of water or juice, and swallowing extended-release tablets whole.
- Check first with kidney disease, heart disease or Addison's disease, the conditions MedlinePlus asks you to mention before taking potassium, and if you take an ACE inhibitor, an ARB or a potassium-sparing diuretic.
- Count salt substitutes as potassium. MedlinePlus asks you to tell your doctor if you use one, because it changes the dose picture.
- If you take a loop or thiazide diuretic, your doctor may already be monitoring both minerals. Ask before adding either.
- If a test shows low potassium that keeps coming back, ask whether magnesium was checked too.
Dosage Considerations
Magnesium: the adult upper limit for supplemental magnesium is 350 mg a day, according to NIH. Food magnesium is not counted in that limit. Larger supplement doses often cause diarrhea, nausea and abdominal cramping. Our magnesium glycinate page covers one of the gentler forms.
Potassium: there is no upper limit for healthy adults, but over-the-counter pills are capped by practice at 99 mg, and multivitamins that contain potassium typically provide about 80 mg. Higher doses are prescription products, dosed and monitored by your doctor, often with blood tests and an ECG, according to MedlinePlus.
FAQ
Can I take magnesium and potassium at the same time?
Yes, if you have healthy kidneys and do not take medicines that raise potassium. No source we checked describes one mineral blocking the other.
Can I take magnesium and potassium at night?
Yes. The sources give no best hour for either. Take potassium with a meal or snack and a full glass of water, which for many people means dinner.
Can I take magnesium glycinate with potassium?
The form of magnesium does not change the answer. Magnesium glycinate and an over-the-counter potassium pill can be taken together, with the same cautions about kidney disease and blood pressure medicines.
Who should not take potassium with magnesium?
People with chronic kidney disease, and anyone taking ACE inhibitors, ARBs or potassium-sparing diuretics such as spironolactone, should ask their doctor before taking either one.
Key Takeaway
Magnesium and potassium are partners, not rivals: low magnesium can drive potassium out through the kidneys, which is why doctors correct both together. For a healthy person, taking them in the same dose is fine. The caution is potassium in people with kidney disease or on ACE inhibitors, ARBs or potassium-sparing diuretics, where blood potassium can rise too high, so check with your doctor first.
Track Your Timing
Supplement Tracker lets you schedule magnesium and potassium as separate supplements, each with its own reminder, at whatever meal suits you. If your doctor adjusts a dose after a blood test, you can change that one schedule without touching the other.
