Older Adults on SSRIs: How to Prevent Hyponatremia and Falls

Every year, hundreds of thousands of older adults in the U.S. start taking SSRIs to manage depression or anxiety. These medications help many feel better-but for some, they bring hidden dangers. The biggest risks? Hyponatremia and falls. Both can turn a simple treatment into a life-threatening event. And the worst part? Many of these cases are preventable.

What Is Hyponatremia-and Why Does It Happen With SSRIs?

Hyponatremia means your blood sodium level drops too low-below 135 mmol/L. Sodium is crucial for keeping your nerves, muscles, and fluids balanced. When it dips, your body holds onto too much water. That’s exactly what SSRIs can trigger.

SSRIs cause something called SIADH-Syndrome of Inappropriate Antidiuretic Hormone Secretion. Normally, your kidneys adjust how much water they keep or flush out. But with SSRIs, your body keeps releasing too much ADH (antidiuretic hormone), so your kidneys hang onto water like a sponge. That dilutes the sodium in your blood.

This doesn’t happen to everyone. But in older adults, it’s far more likely. Why? Because aging changes how your body handles fluids. You have less total body water. Your kidneys don’t filter as well. Your hormones don’t respond as sharply. All of this makes you more sensitive to even small changes in sodium.

Studies show older adults on SSRIs are more than twice as likely to develop hyponatremia compared to those not taking these drugs. About 6 out of every 100 seniors on SSRIs will have low sodium levels. In about 1 out of 100, it gets severe enough to cause confusion, seizures, or coma.

Which SSRIs Carry the Highest Risk?

Not all SSRIs are created equal when it comes to hyponatremia risk.

Fluoxetine (Prozac) has the highest reported risk among SSRIs-nearly 3.6 times more likely to cause low sodium than other antidepressants. Sertraline (Zoloft) and paroxetine (Paxil) also carry moderate risk. Escitalopram (Lexapro) and citalopram (Celexa) are a bit safer, but still risky for older adults.

Even SNRIs like venlafaxine (Effexor) are worse than most SSRIs. If you’re over 65 and your doctor suggests an antidepressant, knowing which one carries the least risk matters.

Mirtazapine (Remeron) is often the best alternative. It’s not an SSRI, and studies show it rarely causes hyponatremia. Bupropion (Wellbutrin) is another option with low sodium risk-but it doesn’t work as well for everyone, especially those with severe anxiety.

Who’s Most at Risk?

Some people are far more likely to develop hyponatremia on SSRIs. Watch out if you have:

• Low starting sodium levels (below 140 mmol/L)
• Body weight under 68 kg (150 lbs)-especially if you’re female
• Take a thiazide diuretic (like hydrochlorothiazide) for high blood pressure
• Have kidney problems or heart failure
• Started or increased your SSRI dose in the last 2-4 weeks

The combination of SSRIs and thiazide diuretics is especially dangerous. Together, they raise hyponatremia risk by over 20%. That’s not a coincidence-it’s a known danger zone.

How Hyponatremia Leads to Falls

Low sodium doesn’t always cause obvious symptoms like nausea or vomiting. In older adults, it often shows up as:

• Dizziness when standing up
• Feeling weak or unsteady on your feet
• Confusion or trouble thinking clearly
• Falling more often than usual

These aren’t just “getting older” signs. They’re red flags for hyponatremia. And they directly increase fall risk.

Falls in seniors are one of the leading causes of hip fractures, hospital stays, and long-term disability. A single fall can end independence. And if hyponatremia is the hidden cause, no amount of home safety mods-grab bars, rugs removed, better lighting-will fix the real problem.

Studies show that seniors with low sodium are significantly more likely to fall. Even mild hyponatremia (130-134 mmol/L) can impair balance and reaction time enough to cause a stumble. And because the symptoms are subtle, they’re often missed-until it’s too late.

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

Experts agree: Before starting an SSRI, check the patient’s sodium level. Then check it again two weeks later. That’s the bare minimum.

But here’s the problem: Many doctors don’t do this. A 2023 study found that while 80% of clinics have guidelines for sodium monitoring in seniors on SSRIs, only about 30% actually follow them. Why? Time. Cost. Lack of reminders in electronic health records.

Some hospitals have fixed this. Johns Hopkins Bayview Medical Center added automated alerts in their system. When a doctor prescribes an SSRI to someone over 65, the system flags: “Check sodium before and at 2 weeks.” They saw a 22% drop in ER visits for hyponatremia within a year.

The American Society of Health-System Pharmacists created a tool now used in over 120 hospitals that automatically warns doctors if they prescribe an SSRI with a thiazide diuretic. That alone cut risky prescriptions by nearly 19%.

Yet, many primary care doctors still don’t know about these tools-or aren’t using them.

What You Can Do as a Patient or Family Member

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

1. Ask for a blood test before starting any SSRI. Request a basic metabolic panel (BMP)-it includes sodium.
2. Ask for a repeat test two weeks after starting or after any dose increase.
3. Know the warning signs: dizziness, confusion, weakness, frequent stumbling. Don’t brush them off as “just aging.”
4. Review all medications. If you’re on a water pill (hydrochlorothiazide, chlorthalidone), ask if it’s safe with your antidepressant.
5. Ask about alternatives. If you’re high-risk, ask if mirtazapine or bupropion might be better.

If you’ve had a fall recently and are on an SSRI, get your sodium checked-even if you feel fine.

The Big Contradiction: Why Monitoring Alone Isn’t Enough

Here’s the frustrating part. A 2023 study showed that even when doctors followed the guidelines and checked sodium levels, it didn’t reduce hospitalizations. Why?

Because finding low sodium isn’t the end-it’s the beginning. If you detect it but don’t act, nothing changes.

The real solution isn’t just testing. It’s:

• Stopping the SSRI if sodium drops below 130
• Restricting fluid intake if it’s mild
• Switching to a safer antidepressant
• Monitoring closely for signs of worsening symptoms

Many patients get the test, get the result, and then nothing happens. No follow-up. No plan. No change in meds. That’s when the danger grows.

What’s New in 2025?

New tools are emerging. The Geriatric Antidepressant Safety Collaborative launched an AI tool that predicts who’s most at risk. It looks at age, sodium levels, fall history, kidney function, and current meds-and flags high-risk patients before they even start an SSRI.

The American Geriatrics Society updated its guidelines in 2024 to say: “Consider fall history when choosing an antidepressant.” That’s huge. For the first time, doctors are being told to think about mobility-not just mood-when prescribing.

And the NIH just funded a $2.8 million study to finally answer the question: What monitoring protocol actually saves lives? Results aren’t due until 2027, but the hope is clear: better rules, better tools, better outcomes.

Bottom Line: Safety Comes Before Speed

SSRIs can help older adults feel like themselves again. But they’re not harmless. The risk of hyponatremia-and the falls that follow-is real, preventable, and often ignored.

If you or someone you love is on an SSRI:

• Don’t assume it’s safe just because it’s common.
• Don’t wait for symptoms to appear.
• Ask for sodium testing before and after starting.
• Speak up if dizziness or falls start happening.
• Ask about safer alternatives.

Your life isn’t just about feeling less depressed. It’s about staying steady on your feet, thinking clearly, and living safely. That starts with asking the right questions-and making sure someone listens.