Symptoms of Low Blood Sodium Levels (aka Hyponatremia) and When to Seek Treatment

We've all heard about how a high-salt diet can wreak havoc on our health. But when the blood's sodium concentration falls lower than normal — a condition called hyponatremia — that can also lead to adverse health effects.

There are a range of possible causes of low sodium levels. While mild symptoms are easy to dismiss or misdiagnosed, in severe cases, hyponatremia can be life-threatening.

​Read more:​ What Are the Dangers of Low Sodium Levels?

The normal range for blood sodium levels is 135 to 145 milliequivalents per liter (mEq/L), according to the U.S. National Library of Medicine. When sodium levels are low, it causes water to move out of the bloodstream and into your cells. Brain cells are especially sensitive to this change, so your first symptoms might include feeling sluggish or confused, notes the Merck Manual. Other symptoms of mild hyponatremia, according to the Mayo Clinic, include:

• Nausea and vomiting
• Headache
• Irritability
• Restlessness
• Loss of energy
• Drowsiness
• Fatigue
• Muscle weakness
• Muscle spasms or cramps
• Seizures

Symptoms for low blood sodium often don't appear until the blood sodium level drops below 120 mEq/L, per the American Family Physician, and because symptoms are typical of a variety of health problems, many hyponatremia cases can go unnoticed. If left untreated, hyponatremia may worsen, causing muscle weakness and cramps, vomiting, seizures, coma and, in some cases, death.

Low sodium symptoms may vary in severity depending on a number of factors. Older, chronically ill people may experience more symptoms than younger, otherwise healthy people with the same blood sodium level, according to the Merck Manual.

The severity of symptoms also depends on how quickly the sodium levels drop. If someone's sodium levels decline significantly in less than 48 hours (called acute hyponatremia), they'll likely experience symptoms. However, in the case of chronic hyponatremia, in which the levels decline slowly over days, weeks or months, someone may have few, if any, symptoms at all, according to a November 2014 article in the ​Indian Journal of Endocrinology and Metabolism​.

"If it develops a little bit every day, the brain is able to adapt and you're not going to have overt symptoms," Daniel E. Weiner, MD, FASN, an associate professor at Tufts University School of Medicine and a member of the American Society of Nephrology's Quality Committee, explains. Some people with chronic hyponatremia report subtle symptoms, like slightly impaired balance or mild cognitive defects, "but nothing that's going to be obvious on a cursory exam," says Dr. Weiner.

The Mayo Clinic recommends that you visit the emergency room if you develop any of the severe signs and symptoms of hyponatremia, such as nausea and vomiting, confusion, seizures or loss of consciousness. The treatment for hyponatremia depends on the underlying cause and the severity of symptoms.

If you have a medical condition or are taking a medication that puts you at an increased risk of hyponatremia, you should alert your doctor if you have nausea, headaches, cramping or weakness to determine if you need immediate treatment. And be sure to get tested for normal sodium levels regularly​.​

​Read more:​ Can Eating Salty Foods Help Treat Low Blood Sodium Levels?