9 Possible Causes of Low Sodium and When to Take a Sodium Supplement

While most Americans generally eat more sodium than they need, there are situations and medical conditions that can make your sodium levels drop too low.

When there's too much fluid in your body, sodium levels get diluted in your blood, causing low levels of sodium, or a condition known as hyponatremia.

"Treatment usually focuses on correcting fluid balance, but sometimes, giving someone more salt in the form of a salt supplement can help the body correct sodium levels," says Melanie Betz, RD, CSR, FAND, a registered dietitian certified in renal nutrition, aka, The Kidney Dietitian.

Here, learn the causes of hyponatremia, how to treat it and when sodium supplements may not be the best choice.

Low sodium levels in your blood can be caused by too much water or fluid in your body, to the point where the fluid actually dilutes the level of sodium in your blood, says Susan Sheehy, RDN, LD, a dietitian with Top Nutrition Coaching.

Hyponatremia can happen for various reasons, such as:

Drinking lots of beverages that don't have electrolytes (drinking lots of water or alcohol with little food) can cause hyponatremia, says Julie Wright Nunes, MD, MPH, a nephrologist and associate professor of medicine at the University of Michigan and member of the American Kidney Fund's Medical Advisory Committee.

Additionally, a person newly diagnosed with diabetes might feel excessive thirst from elevated blood sugars and end up drinking too much fluid, Sheehy says.

Hyponatremia can happen when your electrolytes (sodium, potassium, chloride, magnesium and calcium) get too high or low.

"This can be caused from things like severe vomiting or diarrhea, fluid retention or edema, heart failure, high blood pressure or dehydration," Sheehy says.

People involved in endurance sports like marathon running are also at higher risk of hyponatremia from drinking lots of water without taking electrolytes.

This could be because "your kidneys are holding onto fluid, or a large amount of fluid was recently ingested," Sheehy says.

When your heart muscle is unable to pump blood to the rest of the body (i.e., heart failure), fluid can build up in the lungs, which dilutes the level of sodium in your blood, Sheehy says.

Your kidneys' main job is to maintain electrolyte balance and blood pressure, Sheehy says.

But if you're in kidney failure, you can get hyponatremia because your kidneys aren't properly doing their job — i.e., filtering waste, maintaining electrolyte balance or removing urine. Fluid then builds up and dilutes the level of sodium in your blood, Sheehy adds.

Sometimes called water pills, diuretics can also cause hyponatremia. But your doctor may still prescribe them if you have a condition that causes you to hold onto fluid — like heart failure or liver damage, per the Mayo Clinic.

"However, along with this (often helpful) fluid loss in your body can come electrolyte loss," Sheehy says. This can lead to less-than-ideal sodium levels.

Cirrhosis is a condition that causes a buildup of scar tissue on your liver, affecting its ability to function properly, per the Cleveland Clinic.

One of the complications of cirrhosis is called ascites — i.e., swelling in your abdomen, per the Cleveland Clinic. This happens when fluid builds up in your body and dilutes your blood levels of sodium, Sheehy says.

Medications like antidepressants (specifically SSRIs) and carbamazepine (to treat epilepsy and mania) may cause a buildup of water in your cells when you first start taking them, which can lead to low sodium levels in your blood, per the Cleveland Clinic.

This illegal recreational drug increases the risk of severe and even fatal cases of hyponatremia because it causes excessive thirst, according to the Mayo Clinic.

Postural orthostatic tachycardia syndrome (also known as POTS) is a condition that causes your heart to beat faster than normal as you change positions (like from sitting or lying down to standing up), affecting the normal control of blood pressure, per the National Institute of Neurological Disorders and Stroke.

"[POTS] can result in fainting and dizziness and can be difficult to manage," Sheehy says. It can also happen for many reasons, including "viruses like COVID-19 and mononucleosis, pregnancy, surgery, trauma or certain autoimmune diseases and hereditary factors," Sheehy adds.

"Often people with POTS have a lower blood sodium level and require sodium supplements along with fluid," she says. This can come in the form of salt tablets or electrolyte drink mixes.

A blood or urine test will show whether you have low sodium levels. If you do have hyponatremia, your doctor will work with you to figure out the best treatment, per the Cleveland Clinic.

Treatment for mild hyponatremia usually includes restricting fluids and/or changing any medications, if they're potentially causing the low sodium levels, Sheehy says.

"These people typically need to lower their sodium intake which, in turn, lowers the excess fluid in their body and normalizes their blood levels of sodium," Sheehy says. "Without the fluid in your body, your blood level of sodium is no longer diluted and becomes more concentrated."

People with severe, acute hyponatremia may need medications to manage their symptoms or an IV of sodium solution at the hospital, to slowly raise the levels in their blood, per the Mayo Clinic.

If you're prescribed an IV treatment, you'll need to be monitored in the hospital to make sure your levels don't spike too quickly, per the Mayo Clinic.

There's a time and place for sodium supplements, but they're not right for everyone.

Some examples of people who may take daily sodium supplements under the supervision of a doctor or registered dietitian include the following, per Sheehy:

• Someone with chronic low blood pressure or dehydration
• Endurance athletes who do sprints or shorter runs
• Someone who works in the heat and is easily dehydrated
• Someone who sweats a lot
• People who have POTS

The supplements doctors recommend often come in different forms — such as capsules, powders, chews or tablets — so you can find one that works best for your needs.

Keep in mind, there isn't an established recommended amount of sodium to correct hyponatremia — which is why you shouldn't take it upon yourself to try sodium supplements without seeing a doctor. They can tell you the severity of your hyponatremia and help you determine how much sodium you actually need.

With sodium supplementation, there's potential for the pendulum to swing in the opposite direction, too, causing a few side effects and risks. These include:

Other than a few specific instances, your doctor often ‌won't‌ recommend sodium supplements for hyponatremia. The first line of treatment usually involves balancing your fluids instead.

Plus, if you take too much sodium, you could get hypernatremia — or high blood levels of sodium (i.e., the opposite of hyponatremia), per Merck Manuals.

"This is much more likely if you don't drink enough water with the salt tablets," Betz says.

Symptoms of hypernatremia include the following, per Betz:

• Weakness
• Dizziness
• Thirst
• Tongue swelling
• Fast heart rate
• High blood pressure

The American Heart Association (AHA) recommends getting between 1,500 and 2,300 milligrams of sodium per day, depending on your health status. (Most Americans get more than that, though, at about 3,400 milligrams per day.)

Getting too much salt can contribute to high blood pressure, which puts you at a higher risk for heart attack, heart failure, stroke, kidney failure or disease and other complications, per the AHA.

Too much sodium in your diet can also contribute to kidney stone formation, because it increases the amount of calcium in your urine, which, when combined with oxalates, form kidney stones, per Harvard Health Publishing.

That's why it's so important to talk to your doctor to make sure that taking sodium tablets is the best and most effective treatment for you.

Remember, the first line of treatment for hyponatremia usually only involves limiting fluid intake — not taking salt tablets. That said, if you're prescribed salt tablets, ‌and‌ restrict your fluids, you can run into a whole host of other issues.

"Routinely taking sodium supplements without fluid can cause stress on the kidneys," Sheehy says. That's why, if your doctor did recommend salt tablets, you must keep drinking water for it to be effective, she adds.

In the end, eating more high-sodium foods might be a safer bet than using sodium supplements.

"If you need more sodium, it's just as effective to add salt to your food or eat a meal higher in sodium as it is to take a salt supplement," Betz says.

According to Betz, most sodium supplements have about 300 to 400 milligrams of sodium. For comparison, she says:

• A 1/4 teaspoon of salt has 575 milligrams of sodium
• A teaspoon of soy sauce has about 300 milligrams of sodium
• And a single-serving bag of potato chips has anywhere from 170 to 250 milligrams of sodium

Some other high-sodium foods include the following, per Betz:

• Pickles
• Sauerkraut
• Meat jerky (like beef or turkey)
• Deli meat
• Tomato or vegetable juice

Sodium supplements are often not the first line of treatment for people with hyponatremia. Instead, low blood sodium levels are treated by cutting back on liquids in mild cases, or getting medications and IV treatment in severe cases.

That said, only a few specific cases of hyponatremia may require salt tablets, and strictly under your doctor's supervision. All in all, sodium supplements aren't often prescribed to treat low sodium levels.

If anything, about 90 percent of the U.S. population is eating way more salt than they need, per the FDA. So taking salt supplements on top of that could be harmful and lead to chronic diseases like high blood pressure, heart disease, kidney disease, stroke and kidney stones.

If you think you might have hyponatremia, work with your doctor to see if you should take sodium supplements or get a different form of treatment.