Salt Matters: Hidden Perils of Antidepressants and Drug-Induced Hyponatremia

We have been told for decades that salt is bad for us! For example, an article in the journal Hypertension (Nov. 8, 2024) points out that high blood pressure is the most important risk factor for cardiovascular disease. The authors strongly advocate for reducing sodium intake to lower blood pressure. We appreciate this public health message, but we worry that many health professionals forget that sodium is also essential for health. When sodium levels drop too low, it can be life threatening. Doctors must warn patients about drug-induced hyponatremia. That’s when medications deplete the body of sodium.

Drug-Induced Hyponatremia Is a Medical Emergency!

Can Prozac (fluoxetine) cause hyponatremia?

At last count, antidepressants such as venlafaxine (Effexor), paroxetine (Paxil), sertraline (Zoloft), citalopram (Celexa), escitalopram (Lexapro) and fluoxetine (Prozac) are taken by by nearly 30 million Americans every day. Such medications can trigger drug-induced hyponatremia.

We suspect that this adverse reaction is especially worrisome during hot weather when people are more likely to sweat a lot. How many health care professionals warn their patients about this potentially life-threatening complication?

This reader experienced drug-induced hyponatremia from fluoxetine:

Q. You’ve written about problems with low sodium levels due to blood pressure pills or even very low-sodium diets. Don’t overlook the dangers of fluoxetine in older people.

I took this antidepressant (as Prozac) when I was in my 30s and had no trouble. In my early 60s, my doctor prescribed it again, and it lowered my blood sodium.

I became confused and thirsty and started to drink more water. As a result of the low sodium, I had to spend six days in the hospital. If I’d been in a rural community, there might not have been a kidney doctor available to figure out what was going on. I could have died!

A. Thanks for bringing this serious side effect of antidepressants to our attention. We fear that many health care providers are not aware of this life-threatening complication.

A recent meta-analysis of 10 studies found that antidepressants like venlafaxine , paroxetine, sertraline, citalopram, escitalopram and fluoxetine are all associated with low blood sodium (Journal of Endocrinological Investigation, April 22, 2025). Doctors call this condition drug-induced hyponatremia.

Symptoms of Hyponatremia:

Symptoms may include confusion, anxiety, fatigue, trouble walking, muscle spasms and nausea. Although blood pressure pills containing diuretics are the most common culprits, antidepressants and proton pump inhibitors for heartburn may also trigger this condition (European Journal of Internal Medicine, May 5, 2025).

People should be especially cautious when the weather gets hot. A blood test can reveal sodium levels.

Diuretics for Hypertension Can Lead to Drug-Induced Hyponatremia:

Hydrochlorothiazide (HCTZ, HCT) is a diuretic (water pill) that is widely prescribed to lower blood pressure. Roughly 50 million prescriptions are written for “thiazide” diuretics annually. That does not count the millions of prescriptions that are filled for other medications that contain HCT along with another drug to control hypertension.

A few examples include lisinopril plus HCT, losartan plus HCT and metoprolol plus HCT. One side effect that is rarely discussed with patients who take hydrochlorothiazide is dangerously low sodium levels (hyponatremia).

What Happens When Sodium Goes TOO Low?

This reader’s sister suffered from a severe symptom because of dangerously low sodium levels:

Q. I would strongly suggest that anyone taking the diuretic hydrochlorothiazide for high blood pressure have the doctor monitor sodium and potassium levels regularly. My sister suffered from extreme nausea for months before it was discovered that her sodium level was extremely low. Her hydrochlorothiazide was discontinued and the nausea abated.

A. Most people with high blood pressure have been told to avoid excess sodium. To do so, they may follow a strict low salt diet.

While too much sodium can drive blood pressure up, diuretics such as hydrochlorothiazide can lower sodium, sometimes too much. Dangerously low sodium levels can lead to nausea. Other symptoms can include headaches, cramping, weakness and even confusion or seizures in extreme cases. A lot of older people may experience weakness, confusion and muscle cramping when the weather gets hot. If they are taking a blood pressure pill, a proton pump inhibitors for heartburn and an antidepressant, they could be suffering drug-induced hyponatremia.

This reader’s mother had a really close call because of dangerously low sodium:

Q. My elderly mother has been very conscientious about a low-salt diet. She never salts her food and is careful not to eat processed foods high in sodium.

Despite this, her doctor diagnosed her with mild high blood pressure and put her on a diuretic called hydrochlorothiazide. Last week she got up in the middle of the night to go to the bathroom. She suddenly felt weak and collapsed. When the paramedics came in response to her call button, she was confused.

They took her to the hospital and discovered that her sodium and potassium levels were perilously low. Could her medicine be responsible for this scary episode?

Dangerously Low Sodium & Potassium Levels:

A. Hydrochlorothiazide (HCTZ, HCT) is one of the most commonly prescribed blood pressure drugs in the world. It is considered safe and cost effective.

Nonetheless, HCTZ could have led to your mother’s low sodium and potassium levels. This medication can cause loss of these crucial electrolytes (Journal of Emergency Medicine, March, 2015).

One population-based study found that those taking this diuretic were five times more likely to develop hyponatremia (low sodium) than those not on it (American Journal of Kidney Diseases, July 2013).

Other Medications That Can Lead to Dangerously Low Sodium Levels:

Other medications may also contribute to hyponatremia. They include some antidepressants, antipsychotics and PPI-type heartburn medicines (Journal of Medical Case Reports, June 29, 2020). Because dangerously low sodium levels lead to life-threatening reactions, prescribers should monitor sodium as well as potassium levels with regular blood tests.

Symptoms of Hyponatremia:

Dangerously low sodium levels can cause nonspecific symptoms. That means it can be hard to diagnose this condition without a blood test. Weakness and confusion are common symptoms of low sodium. Others include loss of appetite, muscle cramps, headache and nausea. If the sodium depletion is severe, seizures or coma may result.

Symptoms of Hypokalemia (low potassium):

Some symptoms of low potassium levels are similar to low sodium levels. Weakness and confusion are red flags. Other symptoms to be alert for include muscle cramps or spasms, numbness or tingling, palpitations or irregular heart rhythms, constipation, thirst, frequent urination or muscle paralysis.

Stories from Readers:

Liz in Raleigh, NC, had a close call:

“BEWARE IF YOU TAKE DIURETICS. On October 29, 2014, I was in my neighbor’s yard around dusk to check on his cat. I fell on something and hit my head, ending up in the trauma intensive care unit for four days. I needed four staples in my head to close the cut.

“I had limited memory before I fell and no memory at all for about three days while in the hospital. The diagnosis: low sodium. Mine was 116. The normal range is 136-145. I had no noticeable signs before I fell that anything was wrong.”

Hyponatremia is diagnosed when sodium levels fall below 135 mEq/L.

Marlene in Florida responded to Liz:

“I almost died two years ago when I had hyponatremia (low sodium in the blood), caused by diuretics prescribed by a new-to-me cardiologist. I had avoided a lot of salt for years. That wasn’t what caused the hyponatremia. It was the diuretics.

“I, like you, suffered memory loss.”

The People’s Pharmacy Perspective:

Many people can take hydrochlorothiazide without experiencing either dangerously low sodium or potassium levels. But we encourage people who are following a low-sodium diet and are taking diuretics to 1) have their blood tested periodically for both sodium and potassium and 2) be alert for symptoms of dangerously low sodium or potassium levels. When in doubt, contact a physician immediately and be tested promptly.

You can learn more about HCTZ side effects here. To learn more about medications for hypertension, you may want to consult our eGuide to Blood Pressure Solutions. This online resource can be found in the Health eGuides section.

If you know someone who has high blood pressure, heartburn or suffers from depression, please make sure they know about drug-induced hyponatremia. If you found this article of value, please send it to friends and family. We would be grateful if you could also encourage them to sign up for our free newsletter at this link. And if you find our articles unique amidst the flood of health information flowing on the web, please consider a donation at this link. Your support enables us to keep alerting people to adverse drug reactions that many health professionals may not always mention.  Thank you!