Overview
Hyponatremia means the sodium level in the blood is lower than normal, often because there is too much water relative to sodium. Sodium helps control fluid balance and nerve and muscle function. Mild cases may cause no symptoms, while a rapid or severe drop can be serious.
Symptoms
- Nausea and vomiting
- Headache
- Confusion or trouble concentrating
- Tiredness and low energy
- Muscle weakness, cramps or spasms
- Restlessness or irritability
- In severe cases, seizures or reduced consciousness
Causes & risk factors
- Certain medicines, including some water pills
- Heart, liver or kidney conditions that affect fluid balance
- Hormonal problems, such as thyroid or adrenal issues
- Drinking excessive amounts of water, including during endurance exercise
- Severe vomiting or diarrhea
- A condition where the body holds onto too much water (SIADH)
Treatment & self-care
A clinician confirms the level with blood tests, assesses your fluid status, and looks for the underlying cause. Treatment depends on how low the sodium is, how quickly it developed, and the cause, and must be corrected carefully under medical supervision. A licensed clinician should direct management, as correcting sodium too quickly can be harmful.
See a doctor urgently if
- You feel confused, very weak, or unusually drowsy
- You have ongoing nausea, headache, or muscle cramps without a clear cause
- Seek emergency care for seizures, fainting, severe confusion, or someone being difficult to wake
This condition can be an emergency. If any of the signs above are severe or getting worse, go to the nearest emergency room now or call your local emergency number — do not wait for an online consultation.