Older Adults on SSRIs: How to Prevent Hyponatremia and Falls

More than 1 in 5 Americans over 65 are taking an SSRI for depression or anxiety. These medications help many people feel better-but they also carry a quiet, dangerous risk: low sodium levels that can lead to falls, confusion, and even death. This isn’t theoretical. It’s happening right now in homes, nursing facilities, and hospitals across the country. And most of the time, no one sees it coming.

Why SSRIs Are Risky for Older Adults

SSRIs like sertraline, fluoxetine, and escitalopram work by increasing serotonin in the brain. That’s good for mood. But serotonin also affects the kidneys. In older adults, this can trigger something called SIADH-syndrome of inappropriate antidiuretic hormone secretion. Basically, the body starts holding onto too much water, diluting the sodium in the blood. When sodium drops below 135 mmol/L, you have hyponatremia.

Older bodies are more vulnerable. They have less total body water. Their kidneys don’t filter as well. Their hormones don’t regulate fluid balance like they used to. All of this makes it easier for even a small change in medication to cause a big drop in sodium. Studies show seniors on SSRIs are more than twice as likely to develop hyponatremia compared to those not taking these drugs. And the risk doesn’t stop there.

The Hidden Link Between Low Sodium and Falls

Hyponatremia doesn’t always cause obvious symptoms like nausea or seizures. In older adults, it often shows up as dizziness, weakness, or unsteady walking. These aren’t just "getting older" signs. They’re red flags.

Think about it: if your sodium is low, your brain doesn’t function as sharply. Your muscles feel weak. Your balance is off. You’re more likely to stumble on a rug, slip in the bathroom, or misstep on stairs. A 2023 study found that nearly 60% of older adults hospitalized for hyponatremia had fallen in the weeks before admission. Many of those falls led to hip fractures, brain bleeds, or long-term disability. And in many cases, the root cause was never checked-because no one tested the sodium.

Who’s Most at Risk?

Not everyone on SSRIs will get hyponatremia. But some people are far more likely to. Here’s who needs extra attention:

• Women-especially those with lower body weight
• People with baseline sodium below 140 mmol/L
• Those taking thiazide diuretics (like hydrochlorothiazide) along with SSRIs
• Individuals with BMI under 25
• Anyone who’s already had a fall or balance issues

The combination of SSRIs and thiazide diuretics is especially dangerous. Studies show this combo increases hyponatremia risk by 24% to 27%. That’s not a small bump. It’s a warning sign that should trigger a medication review.

Which SSRIs Are Riskiest?

Not all SSRIs are created equal when it comes to sodium. Fluoxetine (Prozac) carries the highest risk among SSRIs-nearly 3.6 times more likely to cause hyponatremia than other options. Sertraline and citalopram are also on the higher end. Paroxetine and escitalopram are a bit safer, but still carry risk.

If you’re managing an older adult’s care, consider switching to alternatives with lower hyponatremia risk. Mirtazapine (Remeron) is often the top choice-it doesn’t affect sodium levels the same way and has shown good results for depression in seniors. Bupropion (Wellbutrin) is another option, though it may not help with anxiety as much. Both have fewer side effects related to balance and fluid shifts.

What Should Doctors Do? (And What They Often Don’t)

Guidelines are clear: check sodium before starting an SSRI. Check it again two weeks after starting or increasing the dose. That’s the standard. But here’s the problem: many doctors don’t do it.

A 2023 study found that even though hospitals and clinics had protocols for sodium monitoring, only about 30% of them followed through consistently. Why? Time. Staffing. Lack of reminders. Too many patients. Too little support.

Some places are fixing this. Johns Hopkins Bayview Medical Center added automated alerts in their electronic system. When a doctor prescribed an SSRI to someone over 65, the system popped up: "Check sodium before and in 14 days." They saw a 22% drop in hyponatremia-related ER visits in just one year.

The American Society of Health-System Pharmacists built a similar tool now used in over 120 hospitals. It flags dangerous drug combos and reminds clinicians to order tests. In six months, high-risk prescribing dropped by nearly 19%.

What Patients and Families Can Do

You don’t need to wait for your doctor to act. Here’s what you can do today:

• Ask: "Has my sodium been checked since I started this medication?"
• Ask: "Could this medicine make me dizzy or unsteady?"
• Ask: "Is there a safer alternative for someone my age?"
• Watch for new dizziness, confusion, or weakness-especially in the first few weeks after starting or changing the dose.
• If you’ve fallen recently, tell your doctor-even if you think it was "just a slip." 

Many older adults don’t connect their falls to their meds. They blame aging, arthritis, or bad floors. But if you’re on an SSRI and you’ve started stumbling, that’s not normal. It’s a signal.

What Happens If Sodium Drops Too Low?

Mild hyponatremia (125-134 mmol/L) usually means stopping the SSRI and cutting back on fluids. Most people recover fully.

But if sodium drops below 125 mmol/L, it becomes an emergency. The brain swells. Seizures can happen. Coma. Even death. And correcting sodium too fast can cause another deadly problem-osmotic demyelination syndrome, where the brain’s protective coating gets destroyed.

That’s why treatment must be slow and controlled. That’s why hospitalization is often needed for severe cases. That’s why catching it early is everything.

The Big Contradiction

Here’s the frustrating part: some studies say routine sodium testing doesn’t reduce hospitalizations. That doesn’t mean testing is useless. It means we’re not acting on the results.

If you check sodium and see it’s 132-and do nothing-you’ve done nothing. But if you check sodium, see it’s 132, switch the medication, and educate the patient? That’s prevention.

The real issue isn’t monitoring. It’s response. We need systems that don’t just flag low sodium-they trigger action. A phone call. A follow-up visit. A medication change. Without that, testing is just paperwork.

What’s Changing in 2025?

The American Geriatrics Society updated its guidelines in June 2024 to say: if an older adult has a history of falls, consider that before choosing an antidepressant. That’s a big step.

The NIH just launched a $2.8 million study to find out exactly which monitoring protocols actually save lives. And AI tools are being built to predict who’s most at risk-using sodium levels, fall history, medications, and even walking speed data from smart watches.

Meanwhile, demand for safer antidepressants is rising. By 2027, experts predict a 27% jump in prescriptions for alternatives like mirtazapine and psychotherapy-though access remains a challenge for many seniors without transportation or tech skills.

The Bottom Line

SSRIs help people feel better. But they can also make them sicker-if we don’t pay attention. For older adults, the risk of hyponatremia isn’t rare. It’s common. And the link to falls isn’t theoretical. It’s deadly.

Prevention isn’t complicated. It’s simple:

• Test sodium before and two weeks after starting an SSRI.
• Switch medications if the patient is high-risk or already has low sodium.
• Watch for dizziness-it’s not just aging.
• Ask questions-yours and your doctor’s.

If you’re caring for an older adult on an SSRI, don’t wait for a fall to happen. Check the numbers. Talk to the doctor. Push for a safer option. Because sometimes, the medicine meant to lift the spirit can lower the body-and that’s a fall no one should have to recover from.