Quick answer

NIH lists 2,800 mg of potassium a day while breastfeeding. The potassium chloride label says normal milk holds about 13 mEq per liter and supplements should have little or no effect on it. LactMed has separate entries for diclofenac, acesulfame and vitamin K. Ask your doctor about any product.^1,2,3

Key facts

NIH lists 2,800 mg of potassium a day for breastfeeding women and 2,500 mg for breastfeeding teens.¹
The potassium chloride label says supplemental potassium joins the body's pool and, if body potassium is not excessive, should have little or no effect on the level in milk.²
The potassium citrate label says it is not known whether the drug affects the potassium in human milk.⁴
LactMed says most reviewers consider diclofenac, an anti-inflammatory drug sold as diclofenac potassium, acceptable during breastfeeding.³
LactMed says vitamin K, a different nutrient from potassium, is not an adequate substitute for vitamin K given directly to a newborn.⁵

What does NIH list for breastfeeding?

Women need about 2,600 mg of potassium a day from all sources, 2,900 mg during pregnancy and 2,800 mg while breastfeeding.^1,6

The adequate intake for breastfeeding teens is 2,500 mg a day. NIH says potassium leaves the body mainly in urine, and that the kidneys pass the excess in healthy people with normal kidney function.^1,6

What do the potassium chloride and citrate labels say about milk?

The prescription potassium chloride label says the normal potassium content of human milk is about 13 mEq per liter. Because potassium from oral supplements becomes part of the body's potassium pool, it says that as long as body potassium is not excessive, the contribution of supplementation should have little or no effect on the level in milk.²

The potassium citrate label says it is not known whether the drug has an effect on that content, and that it should be given to a woman who is breastfeeding only if clearly needed. Both labels are for prescription drugs, and most supplements hold 99 mg or less per serving.^4,6

What about diclofenac potassium, acesulfame potassium and vitamin K?

Each of these shares a letter or a word with the mineral, and each has its own LactMed entry. For diclofenac, which is sold as diclofenac potassium, LactMed says data on milk levels are poor but appear quite low, that most reviewers consider it acceptable during breastfeeding, and that other agents with more published information may be preferred for a newborn or preterm infant.³

For acesulfame, LactMed says it appears in variable amounts in milk when mothers drink sweetened beverages and is not likely to push an infant past its acceptable daily intake, but diet drinks might raise the risk of vomiting in breastfed infants, and some authors suggest limiting nonnutritive sweeteners while nursing because infant effects are unknown.⁷

Vitamin K is a separate vitamin, not a form of potassium. LactMed says maternal supplements are typically not needed to meet the recommended intake, that 5 mg a day raises milk levels, and that maternal vitamin K is not an adequate substitute for vitamin K given directly to the newborn.⁵

Can too much potassium be a problem for a nursing mother?

Too much potassium in the blood (hyperkalemia) can cause muscle weakness, paralysis, heart palpitations, a burning or prickling feeling in the hands and feet, and irregular heart rhythms that can be life threatening. It can also cause no symptoms until it is severe.⁶

NIH says people with kidney disease or those using ACE inhibitors or potassium-sparing diuretics can develop high blood potassium at ordinary food intakes. Salt substitutes can also add a lot, at about 440 to 2,800 mg of potassium per teaspoon.⁶

Who should ask a doctor about potassium while breastfeeding?

Anyone with kidney disease or taking a medicine that changes potassium, such as an ACE inhibitor, an ARB or a diuretic.⁶
Anyone planning to use a salt substitute or a potassium product.⁶
Anyone who wants to use a pain reliever such as diclofenac, or who drinks several diet drinks a day.^3,7

Ask your doctor or pharmacist, and bring the labels of everything you take.

Questions people ask

Is potassium chloride safe while breastfeeding?

The prescription label says supplemental potassium should have little or no effect on the potassium in milk as long as body potassium is not excessive. Ask your doctor, especially with kidney disease.²

Is potassium citrate safe while breastfeeding?

The prescription label says it is not known whether potassium citrate affects the potassium in milk and that it should be given to a woman who is breastfeeding only if clearly needed. Ask your doctor.⁴

Is diclofenac potassium safe while breastfeeding?

LactMed says milk levels of diclofenac appear quite low and most reviewers consider it acceptable during breastfeeding, though agents with more published information may be preferred for a newborn. Ask your doctor.³

Is acesulfame potassium safe while breastfeeding?

LactMed says acesulfame is not likely to push an infant past its acceptable daily intake, but diet drinks might raise the risk of vomiting in breastfed infants. Ask your doctor.⁷

Is vitamin K safe while breastfeeding?

LactMed says maternal supplements are typically not needed to meet the recommended intake, and that maternal vitamin K cannot replace the vitamin K given to a newborn directly. Ask your doctor.⁵

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This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.