Salt Questions · Health & nutrition
What are the signs of a sodium deficiency?
Short answer
Low blood sodium, called hyponatremia, can cause nausea, headache, confusion, tiredness, muscle weakness or cramps, and in severe cases seizures or coma. It is usually caused by drinking too much water, certain medicines, or illnesses affecting the kidneys, heart or hormones, not by eating too little salt. Severe symptoms need urgent medical care.
Blood sodium (mEq/L)
- 1Below 135: hyponatremia
- 2Normal range 135–145
- 3Above 145: high
What counts as low
Normal blood sodium is about 135 to 145 milliequivalents per litre (mEq/L). Hyponatremia means a level below 135.
Symptoms
- Nausea and vomiting
- Headache
- Confusion, low energy, fatigue
- Restlessness and irritability
- Muscle weakness, spasms or cramps
- Seizures or coma (severe cases)
Common causes
Drinking very large amounts of water (for example during endurance events), diuretics and some antidepressants, heart failure, kidney or liver disease, hormone problems and severe vomiting or diarrhea. Healthy people eating an ordinary diet very rarely become sodium deficient from food alone.
Hyponatremia is diagnosed with a blood test. Don't try to treat suspected low sodium with salt at home; see a doctor.
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The Salt Almanac. (2026, November 8). What are the signs of a sodium deficiency. https://saltalmanac.com/answers/what-are-the-signs-of-a-sodium-deficiency
“What are the signs of a sodium deficiency.” The Salt Almanac, 8 Nov. 2026, saltalmanac.com/answers/what-are-the-signs-of-a-sodium-deficiency. Accessed [today's date].
“What are the signs of a sodium deficiency.” The Salt Almanac. Last modified November 8, 2026. https://saltalmanac.com/answers/what-are-the-signs-of-a-sodium-deficiency.
Original sources
- Mayo Clinic. Hyponatremia: symptoms and causes. https://www.mayoclinic.org/diseases-conditions/hyponatremia/symptoms-causes/syc-20373711
- Wikipedia. Hyponatremia. https://en.wikipedia.org/wiki/Hyponatremia