How do you tell if you need salt? The signs and symptoms of low sodium

October 8, 2025 •

3 min read

While excessive sodium intake is widely discussed, a dangerous condition called hyponatremia—where blood sodium levels are too low—can cause serious health issues. Knowing how do you tell if you need salt is crucial for maintaining proper bodily function, especially since symptoms can be subtle at first.

Quick Summary

Low blood sodium, or hyponatremia, is caused by excessive water consumption, certain medications, or underlying health issues, and presents with symptoms like nausea, headaches, confusion, and muscle cramps.

Key Points

Hyponatremia is Low Sodium: Low blood sodium, or hyponatremia, occurs when sodium concentration falls below 135 mEq/L, which can cause cells to swell.
Common Symptoms Include Fatigue and Cramps: Mild to moderate hyponatremia often presents with non-specific symptoms like fatigue, headaches, nausea, and muscle weakness or cramps.
Severe Symptoms Require Immediate Attention: Serious signs, such as seizures, extreme confusion, or loss of consciousness, indicate a medical emergency.
Causes Vary from Exercise to Illness: Excessive sweating, over-hydrating with plain water, taking certain medications, and chronic conditions like heart or kidney failure can all cause low sodium levels.
Low Sodium is Different from Dehydration: While both can cause fatigue, dehydration is a lack of water, which raises sodium levels (hypernatremia), while hyponatremia is often caused by fluid overload.
Diagnosis Needs a Doctor: A blood test is required to confirm low sodium levels, and a medical professional should determine the underlying cause and appropriate treatment plan.
Balance is Key: Most modern diets contain enough salt, but individuals who exercise heavily or have specific health conditions may need to pay closer attention to their electrolyte balance.

Sodium is an essential electrolyte that plays a vital role in regulating fluid balance, blood pressure, nerve function, and muscle contractions. Although most modern diets contain an abundance of sodium from processed foods, certain circumstances—including intense exercise, illness, and some medical conditions—can lead to dangerously low levels. This article details the symptoms of low sodium and explains how to differentiate them from other common ailments.

Understanding Low Sodium (Hyponatremia)

Hyponatremia is the medical term for a low concentration of sodium in the blood, typically defined as a level below 135 mEq/L. When sodium levels drop too low, it can cause cells throughout the body, including in the brain, to swell with excess water, potentially leading to severe complications.

Common Symptoms of Low Sodium

Early signs of low sodium are often non-specific and can be confused with other conditions. Be mindful of these indicators, particularly if you have risk factors for hyponatremia.

Nausea and Vomiting: A persistent feeling of sickness is an early sign.
Headache: Mild to moderate headaches can indicate low sodium.
Fatigue and Low Energy: Feeling unusually tired despite rest can signal an electrolyte imbalance.
Muscle Weakness, Spasms, or Cramps: Low sodium can cause involuntary muscle movements or painful cramps.
Confusion and Irritability: Changes in mental status can occur as the condition progresses.

More Severe and Acute Symptoms

Critically low sodium levels require immediate medical attention. Severe symptoms include:

Seizures: Low sodium can disrupt brain function and trigger seizures.
Significant Confusion or Loss of Consciousness: Swelling of brain cells can lead to disorientation or coma.
Extreme Fatigue: A sudden overwhelming feeling of exhaustion can indicate a rapid decline in sodium levels.

What Causes Low Sodium?

Various factors can contribute to low sodium.

Excessive Sweating: Significant sodium loss can occur through intense exercise or heat. Replacing lost fluids with too much plain water can dilute sodium levels.
Certain Medications: Diuretics, antidepressants, and pain medications can interfere with sodium regulation.
Underlying Medical Conditions: Conditions like heart failure, kidney or liver disease, and hormonal disorders can affect fluid balance.
Drinking Too Much Water: Over-hydration without electrolyte replenishment is a common cause, especially for athletes.
Chronic Diarrhea or Vomiting: These can lead to significant fluid and electrolyte loss.

Comparing Low Sodium to Dehydration

Dehydration and low sodium share some symptoms but are distinct conditions. Proper identification is crucial for treatment.


Characteristic	Low Sodium (Hyponatremia)	Dehydration (Hypernatremia)
Cause	Excessive fluid intake, especially plain water, that dilutes sodium levels; loss of sodium through sweat or illness.	Loss of body water without an equal loss of sodium. Insufficient fluid intake.
Thirst	Not always a dominant symptom, or may be mild.	Excessive thirst is a key indicator.
Urine Output	Can be low as the body tries to retain fluid.	Significantly reduced urine output.
Mental State	Confusion, irritability, lethargy.	Irritability, restlessness, potential confusion.
Blood Sodium Levels	Below the normal range of 135 mEq/L.	Above the normal range of 145 mEq/L.

Nutritional Sources of Sodium

Sodium is naturally present in foods and added to many processed products. For those concerned about deficiency or who exercise heavily, consider sources like:

Processed Foods: Items like cold cuts, pizza, and soups are high in sodium.
Condiments: Soy sauce and salad dressings contain significant sodium.
Dairy Products: Milk and cheese naturally contain some sodium.
Meat, Poultry, and Seafood: Processed varieties like bacon and cured meats are high in sodium.
Electrolyte Drinks: Sports drinks can replenish sodium for athletes who sweat excessively.

When to Seek Medical Attention

Consult a healthcare professional for chronic fatigue, frequent muscle cramps, or persistent headaches. For severe symptoms like confusion, seizures, or loss of consciousness, seek emergency care immediately. A doctor can use a blood test to check sodium levels and diagnose the cause.

Conclusion: Finding the Right Balance

While reducing excessive sodium is important, recognizing the signs of low sodium is also crucial. The body needs salt for normal function, but extreme restriction or certain factors can cause imbalance. Pay attention to symptoms and seek professional guidance when necessary.

For more information, consult authoritative sources like the Mayo Clinic's guide to hyponatremia.

Frequently Asked Questions

The most common cause is drinking too much water in a short time, which dilutes the body’s sodium levels. It can also be caused by excessive sweating during exercise, certain medications, and underlying health conditions like heart or kidney disease.

Yes, fatigue, low energy, and persistent headaches are some of the most common early symptoms of hyponatremia. They often occur gradually, especially if the sodium level drops slowly.

A key difference is thirst. In dehydration (hypernatremia), you usually feel very thirsty. With low sodium (hyponatremia), excessive thirst may not be present, and symptoms like nausea, confusion, and muscle issues may be more pronounced.

Salt cravings can be a sign of low sodium, but they can also be triggered by other factors like stress, sleep deprivation, or hormonal changes. If persistent and accompanied by other symptoms, it's worth investigating with a doctor.

For mild symptoms, a doctor might recommend increasing salt intake through food or an electrolyte drink, and possibly restricting plain fluid intake. For severe symptoms like confusion or seizures, immediate medical help is necessary.

A doctor can diagnose hyponatremia with a simple blood test that measures your blood sodium concentration. They will also perform a physical exam and review your medical history to determine the underlying cause.

No, while endurance athletes are at risk, low sodium can affect anyone. Older adults, people with certain medical conditions, and those on specific medications are also at a higher risk of developing hyponatremia.