Summary
-
What does potassium do?
Potassium is a mineral and electrolyte that is essential for the proper functioning of the nervous system, skeletal system, heart, and metabolism, as well as maintaining normal blood pressure (see What It Is). Symptoms of potassium deficiency can include muscle weakness, irregular heartbeat, listlessness, mood changes, irrational behavior, nausea, and vomiting. -
Do I need to take a potassium supplement?
Potassium supplements are typically used only to treat or prevent potassium deficiency. Sufficient amounts of potassium can easily be obtained through the diet, but people taking certain drugs or with conditions affecting the kidneys or gut may be deficient (see What to Consider When Using). Low potassium is also common among people hospitalized with COVID-19. Supplementing with potassium may also help to reduce high blood pressure. The citrate form of potassium may also reduce the risk of kidney stones (see What It Does). -
How much potassium should I take?
For preventing potassium loss, potassium is often recommended at doses of 200 to 400 mg, taken 3 to 4 times daily (for a total daily dose ranging from 600 mg to 1,600 mg). For lowering blood pressure in people with hypertension, larger amounts are often used (3,000 mg per day) (see What to Consider When Using). Nearly all common forms of potassium are absorbed equally well (see What to Consider When Buying). 
Best potassium supplement?
As discussed in What CL Found, problems were found with potassium supplements. One could cause you to take 2.5 times as much potassium as you might expect from its label. Pills of the other product would not fully break apart within the allotted time, suggesting the ingredients might be less available for absorption. None of the products exceeded limits for contamination with heavy metals (lead, cadmium, and arsenic), unlike our findings in 2016 when we discovered a significant amount of arsenic in a potassium supplement.
Among the products that passed testing, ConsumerLab.com chose three Top Picks.-
Safety and side effects of potassium supplements:
Potassium from supplements may cause diarrhea, nausea, stomach pain, mild gas and vomiting, which may be reduced by taking with meals. Less common side effects include confusion, irregular heartbeat and shortness of breath. People with kidney disease and people taking potassium-sparing diuretics, ACE inhibitors, or trimethoprim/sulfamethoxazole should not take potassium supplements without medical supervision(see Concerns and Cautions).
