For most healthy adults with normal kidneys, yes: you can take magnesium and potassium together, and they often share a bottle. We found no study of the pair and no documented absorption conflict. Their link is inside the body: magnesium helps move potassium across cell membranes, severe magnesium deficiency can cause low potassium, and more than half of people with clinically significant hypokalemia might be low in magnesium; when both are low, they should be treated together. The caution is potassium. With chronic kidney disease, ACE inhibitors such as benazepril, ARBs such as losartan or potassium-sparing diuretics such as spironolactone, potassium can build up (hyperkalemia), so ask your doctor before adding any, salt substitutes included. Most potassium-only supplements contain up to 99 mg, about 2% of the Daily Value. We found no study showing the pair treats cramps.
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.
Check your whole list, not just one pair
Supplement Tracker reminds you of each dose, and its interaction check looks at every supplement you take, with sources from the NIH.
A calf cramp wakes you at 3 a.m. for the second night this week. By breakfast you have a plan built on two minerals: the magnesium glycinate already on your nightstand, plus a potassium tablet from the pharmacy. So can you take magnesium and potassium together, and who needs to check first?
For most healthy adults with normal kidneys, yes. The two often share a bottle, and we know of no conflict between them. The people who should check first are those whose kidneys clear less potassium: anyone with chronic kidney disease, and anyone taking an ACE inhibitor, an ARB or a potassium-sparing diuretic. For them, extra potassium in any form, salt substitutes included, needs a doctor's approval. As for the cramps, we found no study showing that this pair treats them.
Do Magnesium and Potassium Interfere?
No, as far as we can tell. We found no documented absorption conflict and no study of the two taken together, so nothing calls for spacing them hours apart.
Their connection runs through the body instead. The magnesium fact sheet from the NIH Office of Dietary Supplements (ODS) says magnesium "plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm." It adds: "In severe cases, magnesium deficiency can cause hypocalcemia or hypokalemia," meaning low blood calcium or low blood potassium.
The ODS potassium fact sheet sees the same link from the other direction: "More than 50% of individuals with clinically significant hypokalemia might have magnesium deficiency." Its advice for people low in both is short: "In people with hypomagnesemia and hypokalemia, both should be treated concurrently."
That is a reason for a doctor treating low potassium to check magnesium as well. It is not a reason to dose both at home on a hunch. The advice concerns people diagnosed with both, and the doses are the doctor's to set.
Magnesium, Potassium and Muscle Cramps
If cramps brought you here, the reasoning is easy to follow. The transport quoted above matters for muscle contraction, so a potassium and magnesium supplement sounds like a direct fix for a cramping calf.
The evidence is missing, though: we found no study showing that taking magnesium and potassium together prevents or treats muscle cramps. Whether your cramps have anything to do with your mineral levels is a separate question; our guide to magnesium deficiency symptoms covers what a blood test can and cannot tell you.
Who Should Check First
The caution on this page is about potassium, and it starts in the kidneys. No upper limit has been set for potassium; in the words of the ODS sheet, "there is no evidence that high intakes of potassium cause hyperkalemia in adults with normal kidney function." Hyperkalemia means too much potassium in the blood. The picture changes when the kidneys excrete less potassium in the urine. Chronic kidney disease is one cause, and certain medications are another:
- Angiotensin-converting enzyme (ACE) inhibitors such as benazepril and angiotensin receptor blockers (ARBs) such as losartan reduce the potassium excreted in urine, which can lead to hyperkalemia.
- Potassium-sparing diuretics such as amiloride and spironolactone can cause hyperkalemia.
Experts recommend monitoring potassium in people who take these drugs. ODS warns that for anyone whose kidneys or medicines hold potassium back, even dietary potassium below the Adequate Intake can cause hyperkalemia. If ordinary meals can push potassium too high, a tablet on top is a decision for your doctor. The same goes for salt substitutes, which are high in potassium: ODS advises people with kidney disease or on certain medications to consult a provider before using them.
Thiazide diuretics work the other way. They increase potassium loss and can cause hypokalemia, which makes a potassium supplement look like the obvious fix; whether you need one, and how much, is still your prescriber's call.
On the magnesium side, the ODS magnesium sheet notes that "some medications, including diuretics and proton pump inhibitors, can affect magnesium status." The kidneys also regulate magnesium, so kidney disease puts both halves of the pair in your doctor's hands. If you are not sure which group a prescription belongs to, your pharmacist can tell you.
Practical Recommendations
What follows is our suggested approach, not a tested protocol.
- With healthy kidneys and none of the drugs above, take them together if it suits you. A combined product is fine, and so are two bottles taken at once. For magnesium timing, see our guide to the best time to take magnesium.
- If a blood test shows low potassium, ask whether magnesium was checked too, and let the doctor treating it set the doses.
- On an ACE inhibitor, an ARB or a potassium-sparing diuretic, or living with kidney disease, add no potassium without your doctor. That covers potassium tablets, salt substitutes, and any multivitamin or electrolyte powder that lists potassium on the label.
- On a thiazide diuretic or a proton pump inhibitor, ask before you self-correct either mineral.
- Mind magnesium's own interactions. ODS notes that magnesium may interact with oral bisphosphonates, tetracyclines and quinolone antibiotics; ask your pharmacist how to space them.
- Choose a magnesium form that dissolves well. According to ODS, the aspartate, citrate, lactate and chloride forms tend to have higher bioavailability than oxide and sulfate. See our magnesium citrate guide and glycinate versus oxide comparison. If your magnesium comes in a calcium blend, our calcium and magnesium page covers that pairing.
Dosage Considerations
Magnesium: the recommended intake for adults ranges from 310 to 420 mg a day, according to the ODS magnesium sheet. The upper limit for supplemental magnesium is 350 mg a day for adults, counting supplements and medications but not the magnesium in food. The sheet also warns that "high doses of magnesium from dietary supplements or medications can cause diarrhea, nausea, and abdominal cramping." The cramping on that list is in the abdomen, and it is a hint to take less.
Potassium: the Adequate Intake for adults aged 19 to 50 is 3,400 mg a day for men and 2,600 mg for women, per the ODS potassium sheet. Supplements barely touch that. Most potassium-only supplements contain up to 99 mg, and multivitamin/mineral products that include potassium typically provide about 80 mg. Many manufacturers stop at 99 mg, only about 2% of the Daily Value, because the FDA ruled that some potassium chloride drug products above that amount were unsafe: they were associated with small-bowel lesions. A 99 mg potassium supplement cannot stand in for food, which has to supply nearly all of the 2,600 to 3,400 mg. And the missing upper limit rests on normal kidney function; in the groups above, your doctor sets the limit, not the label.
Key Takeaway
For most healthy adults with normal kidneys, magnesium and potassium can be taken together; we found no conflict between them. Their real link is inside the body: severe magnesium deficiency can cause low potassium, so a doctor treating low potassium may check magnesium too. The caution is about potassium, for anyone with kidney disease or on an ACE inhibitor, an ARB or a potassium-sparing diuretic: ask first, and count salt substitutes. For cramps, we found no study showing the pair helps.
Track Your Timing
Supplement Tracker lets you place magnesium and potassium in time-of-day slots, each slot with its own reminder time, and check off every dose as you take it. The dated history then shows what you took and when, which is worth having in front of you when a potassium result comes back or a new prescription joins the list.
