Heart Failure Treatment: Potassium and Magnesium

Medically Reviewed by James Beckerman, MD, FACC on November 19, 2022
2 min read

Potassium and magnesium are often prescribed to heart patients taking diuretics, or ''water pills.'' They replace the electrolytes you lose because of the water pills.

Examples of potassium supplements include:

Magnesium supplements include:

Take potassium and magnesium supplements right after meals or with food. Follow the label on how often to take it. The number of doses you take each day, the time between doses, and how long you take it will depend on which medicines you were prescribed and your condition.

Possible side effects of potassium and magnesium supplements include:

Nausea, vomiting, diarrhea, and abdominal discomfort. If these side effects continue, call your doctor. If you take controlled-release tablets or capsules and have severe vomiting, vomit blood, or have abdominal pain or swelling, stop taking the medication and call your doctor right away.

Black, tarry, or bloody stools. These are signs of stomach bleeding. If you have them, call your doctor right away.

You should also call your doctor if you have:

If you are taking magnesium or potassium supplements, let your doctor know if:

  • You are using a salt substitute (many salt substitutes contain potassium).
  • You are using ACE inhibitors or certain diuretics.
  • You have a kidney disorder.
  • You are taking any other supplements.

While taking potassium or magnesium, have your blood pressure checked regularly as advised by your doctor.

Keep all appointments with your doctor and the lab so that they can see how you're responding to the supplements. Blood tests might be done to help monitor the level and decide on the dose.