Electrolytes

What are the signs of low electrolytes?

Updated 9 Nov 2026

Short answer

The signs depend on which electrolyte is low. Low potassium can cause constipation, tiredness, muscle weakness and a general unwell feeling; severe cases can upset the heart rhythm.[1] Early signs of low magnesium are loss of appetite, nausea, vomiting, tiredness and weakness; later come numbness, cramps and an abnormal heart rhythm.[2] Low blood sodium during long exercise can cause bloating, vomiting, headache and confusion.[3] Common causes of an electrolyte imbalance are vomiting, diarrhea, heavy sweating, some medicines and kidney, heart or liver problems. A blood test called an electrolyte panel measures the main electrolytes.[4]

Sources (4)

  1. Potassium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  2. Magnesium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  3. Exercise-Associated Hyponatremia. Hew-Butler T Front Horm Res, 2019. PMID 32097926
  4. Fluid and Electrolyte Balance. MedlinePlus, US National Library of Medicine, 2024. medlineplus.gov

More about electrolytes

What are electrolytes?Do you need electrolyte drinks every day?What are electrolytes used for?Are electrolyte supplements safe?Do electrolytes help with dehydration from diarrhea?Do electrolyte drinks improve endurance?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.