Older Adults on SSRIs: How to Prevent Hyponatremia and Falls

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More than 1 in 5 older adults in the U.S. are taking an SSRI for depression or anxiety. But for many, the medication that helps their mood may be quietly increasing their risk of a dangerous fall-or worse. Hyponatremia, a drop in blood sodium levels, is one of the most common and overlooked side effects of SSRIs in people over 65. And it doesn’t always come with obvious symptoms. Sometimes, the first sign isn’t nausea or headache-it’s a stumble on the stairs, a trip to the ER after a fall, or a hospital admission for confusion that no one could explain.

Why Older Adults Are at Higher Risk

As we age, our bodies change in ways that make us more sensitive to medications. Our kidneys don’t filter as well. We have less total body water. Our hormones, like antidiuretic hormone (ADH), start to behave unpredictably. These changes mean that even small shifts in fluid balance can throw off sodium levels-and SSRIs make this worse.

SSRIs cause something called SIADH: the syndrome of inappropriate antidiuretic hormone secretion. Normally, ADH tells your kidneys when to hold onto water. But when SSRIs overstimulate this system, your body holds onto too much water. That water dilutes your sodium. Your blood sodium drops below 135 mmol/L-and that’s hyponatremia.

The risk isn’t the same for everyone. Older adults with a low body weight (BMI under 25), women, and those already taking thiazide diuretics (common for high blood pressure) are at highest risk. People with sodium levels starting below 140 mmol/L are also more likely to drop into dangerous territory. One study found that combining an SSRI with a thiazide diuretic increases hyponatremia risk by 24% to 27%. That’s not a small bump-it’s a red flag.

Which SSRIs Are Riskiest?

Not all SSRIs are created equal when it comes to hyponatremia. Fluoxetine (Prozac) carries the highest risk among this class, with an event rate of over 6.5%. Sertraline and citalopram follow closely. Paroxetine and escitalopram have slightly lower rates, but still pose a real danger.

Even SNRIs like venlafaxine (Effexor) are riskier than many doctors realize. While not SSRIs, they’re often prescribed alongside them-and carry a similar or even higher risk of sodium drops.

On the flip side, some antidepressants have much lower hyponatremia risk. Mirtazapine (Remeron) is consistently flagged as one of the safest options for older adults. Bupropion (Wellbutrin) is another alternative, though it doesn’t work as well for everyone, especially those with severe anxiety. If someone has a history of falls, low sodium, or kidney issues, switching to one of these alternatives may be the smartest move.

Hyponatremia Doesn’t Always Show Up in Blood Tests

Here’s the tricky part: many older adults with hyponatremia don’t feel sick. In fact, 30% to 40% of cases show no symptoms at all-until they fall. The subtle signs are easy to miss: slight dizziness when standing, unsteady walking, confusion that comes and goes, or just feeling "off" for no reason. These aren’t signs of dementia. They’re signs of low sodium.

And that’s why falls happen. When sodium drops, brain cells swell. That affects balance, coordination, and judgment. A person might not even realize they’re at risk. They might think, "I’m just getting older," when really, their medication is silently destabilizing them.

A 2024 review found that hyponatremia increases the risk of falls in older adults-but it didn’t quantify the exact number. That’s because no one has run a perfect study yet. But we know this: people with hyponatremia are more likely to fracture a hip, end up in the hospital, or die. And many of those cases could have been prevented.

What Should Doctors Do?

The American Geriatrics Society says SSRIs can be "potentially inappropriate" for older adults with a history of low sodium or fall risk. That’s a strong warning. But here’s the contradiction: some experts say you must check sodium before starting an SSRI and again at two weeks. Others say that even with testing, hospitalizations don’t drop.

Why? Because checking sodium isn’t enough. You need a plan. If the test comes back low, what happens next? Is the medication stopped? Is fluid intake adjusted? Is the patient monitored daily? Too often, the test is done, the result is filed, and nothing changes.

Best practice? Start with a baseline sodium test before prescribing. Then retest at 10 to 14 days. If sodium drops below 135, don’t wait. Talk about alternatives. If it’s below 130, stop the SSRI immediately and refer for medical evaluation. Mild cases (125-134) can often be managed with fluid restriction and close follow-up. Severe cases (below 125) need hospital care-too-fast correction can cause brain damage.

What Can Patients and Families Do?

You don’t need to be a doctor to protect yourself or a loved one. Here’s what you can do:

• Ask: "What’s my sodium level?" before starting any new antidepressant.
• Ask: "Is there a safer option for someone my age?" If you’ve had a fall or feel dizzy, say so.
• Watch for subtle changes: Is Mom walking slower? Is Dad forgetting where he put his keys more than usual? Is he drinking more water than normal?
• Check all medications. Are they on a diuretic? That combo is dangerous with SSRIs.
• If you’re on an SSRI and feel unsteady, don’t brush it off. Tell your doctor. Get a sodium test.

The Bigger Picture

SSRI use in older adults has jumped 34% since 2015. That’s good news for depression treatment-but bad news if we’re not watching for side effects. Hyponatremia-related hospitalizations now cost over $1.2 billion a year in the U.S. alone.

New tools are emerging. Hospitals are using AI systems to flag high-risk combinations-like SSRIs plus thiazides-and automatically prompt sodium tests. Some clinics have cut emergency visits by 22% just by adding routine sodium checks and patient education.

But the real breakthrough will come when we stop treating depression and fall risk as separate problems. They’re connected. A medication that helps mood can also break balance. And if we don’t connect those dots, we’re not helping-we’re harming.

What Comes Next?

The National Institutes of Health just launched a $2.8 million study to figure out the best way to monitor sodium in older adults on antidepressants. Until we have those answers, stick to what we know:

• Test sodium before and two weeks after starting an SSRI.
• Choose safer antidepressants like mirtazapine or bupropion for high-risk patients.
• Never ignore dizziness, confusion, or unsteadiness in an older adult on an SSRI.
• Don’t assume it’s just aging. It might be your medication.

Depression is real. It’s debilitating. But so are falls. So is brain swelling from low sodium. The goal isn’t just to treat the mind-it’s to protect the whole person. That means thinking beyond the prescription pad. It means asking the right questions. And sometimes, it means choosing a different path.

• Tags
• SSRIs
• hyponatremia in elderly
• antidepressants and falls
• SSRI side effects
• elderly depression treatment