What Happens if You Have Too Little Salt in Your Body?

December 11, 2025 •

3 min read

According to the National Kidney Foundation, hyponatremia is the most common electrolyte disorder, with blood sodium levels below 135 milliequivalents per liter. This condition can occur when you have too little salt in your body, disrupting fluid balance and leading to a range of mild to life-threatening symptoms.

Quick Summary

Hyponatremia, or low blood sodium, causes cells to swell by disrupting the body's fluid balance. Symptoms range from mild fatigue and headaches to severe confusion, seizures, and coma, particularly when sodium levels drop rapidly. The condition can result from underlying diseases, medication side effects, or excessive water intake.

Key Points

Cellular Swelling: Low sodium causes water to move into cells, particularly brain cells, causing them to swell, which is the root cause of many symptoms.
Diverse Symptoms: Hyponatremia symptoms vary widely, from fatigue, headache, and nausea in mild cases to severe confusion, seizures, and coma in critical situations.
Underlying Causes: While a low-salt diet is a potential factor, hyponatremia is often caused by medical conditions such as kidney, heart, or liver disease, hormonal issues (like SIADH), or certain medications.
High-Risk Individuals: Older adults, endurance athletes, and people with certain chronic diseases or on specific medications are at increased risk.
Treatment Varies: Treatment depends on the cause and severity. It can involve fluid restriction, medication adjustments, or careful intravenous sodium solutions in a hospital setting for severe cases.
Hyponatremia vs. Dehydration: Unlike dehydration (loss of both water and salt), hyponatremia results from an excess of water relative to the amount of sodium, emphasizing the importance of electrolyte balance.
Preventive Measures: Managing underlying health conditions, maintaining proper hydration with electrolytes during intense exercise, and monitoring medication effects are crucial for prevention.

The Critical Role of Sodium and What Goes Wrong

Sodium is a vital electrolyte essential for maintaining the body's fluid balance, nerve function, and muscle contraction. When blood sodium concentration drops below the normal range of 135–145 mEq/L, this imbalance is called hyponatremia. Hyponatremia causes fluid outside cells to decrease, leading water to enter cells. This can cause dangerous swelling, especially in brain cells. Symptoms are often more severe if sodium levels drop quickly (acute hyponatremia) compared to a gradual decrease (chronic hyponatremia).

Common Signs and Symptoms

Symptoms of hyponatremia can vary and worsen as sodium levels fall. Common signs include:

Nausea and vomiting.
Headache.
Fatigue and low energy.
Confusion and irritability.
Muscle weakness, cramps, or spasms.
Restlessness.
Seizures in severe cases.
Coma and death in the most critical situations.

Causes of Low Sodium Levels

Hyponatremia isn't always about dietary salt intake. It can result from various factors, including excessive water consumption, especially during exercise, which dilutes sodium. Medical conditions like heart, kidney, and liver diseases can cause fluid retention and dilute sodium. The syndrome of inappropriate anti-diuretic hormone (SIADH) also leads to excess water retention. Additionally, certain medications such as diuretics, antidepressants, and pain relievers can affect sodium balance.

How Hyponatremia Differs From Dehydration

Hyponatremia and dehydration both involve fluid balance but are distinct conditions. Correctly identifying each is vital for treatment, as therapies differ.


Feature	Hyponatremia	Dehydration (Hypernatremia)
Core Imbalance	Too much water relative to sodium, or excessive sodium loss	Too little water relative to sodium
Body Fluid Levels	Fluid may be normal, low, or high, but blood sodium is low	Both water and electrolytes are low, with water loss being predominant
Fluid Shifts	Water shifts into cells, causing them to swell	Water shifts out of cells, causing them to shrink
Primary Symptom	Fatigue, confusion, nausea; thirst is not always present	Intense thirst is a primary symptom
Key Concern	Cerebral edema (brain swelling) due to cells swelling	Inadequate tissue perfusion and potential organ damage from cell shrinkage
Correction	Careful, gradual correction of sodium, often with IV saline	Fluid replacement to address water deficit

Treatment and Prevention

Treatment depends on the cause and severity. Mild cases might involve limiting fluids and treating the underlying cause. Severe, acute hyponatremia requires medical care, potentially including intravenous fluids, with careful monitoring to avoid rapid sodium correction which can cause neurological issues. Chronic cases often involve gradual correction through fluid restriction, medication changes, or managing conditions like heart or kidney failure.

Preventing hyponatremia involves recognizing risk factors. Older adults, endurance athletes, and those with chronic illnesses are at higher risk. Staying properly hydrated during exercise with electrolytes, managing health conditions, and discussing risks with your doctor, especially if on diuretics, are important. Regular blood tests may be needed for at-risk individuals. For those with existing conditions, controlling fluid intake and maintaining a balanced diet are key.

Conclusion

Having too little salt, or hyponatremia, is a serious medical condition disrupting fluid and electrolyte balance. The resulting cellular swelling, particularly in the brain, can cause symptoms from fatigue to life-threatening seizures and coma. Understanding causes like underlying health issues, medications, or excessive water intake is vital for prevention and treatment. While mild cases can be managed, severe hyponatremia requires careful medical supervision. Awareness of symptoms and risk factors is crucial for timely intervention. Seek professional medical advice if you suspect hyponatremia.

Optional Outbound Link: For additional information on sodium's role in the body, visit the MedlinePlus medical encyclopedia.

Frequently Asked Questions

The medical term for having too little salt (sodium) in your blood is hyponatremia, defined as a serum sodium concentration below 135 mEq/L.

When blood sodium levels drop, water moves into brain cells, causing them to swell. This leads to symptoms like confusion, headache, and in severe cases, brain swelling (cerebral edema), seizures, and coma.

Yes, drinking excessive amounts of plain water can cause hyponatremia by overwhelming the kidneys' ability to excrete water, effectively diluting the sodium in the bloodstream.

Early or mild symptoms of hyponatremia can include nausea, vomiting, fatigue, headache, and irritability. These can be easily mistaken for other health issues.

No, they are different conditions. While dehydration is a loss of both water and electrolytes, hyponatremia is an imbalance where there is too much water relative to the amount of sodium in the body.

Individuals at a higher risk include older adults, people with chronic diseases such as heart or kidney failure, endurance athletes, and those taking certain medications like diuretics.

Treatment varies by severity and cause. Mild cases may require fluid restriction, while severe cases may involve intravenous sodium solutions in a hospital setting. The underlying medical condition must also be addressed.

If left untreated, severe hyponatremia can lead to life-threatening complications, including severe brain swelling, seizures, coma, and death.