Older Adults on SSRIs: How to Prevent Hyponatremia and Falls

Every year, more older adults are prescribed SSRIs for depression or anxiety. By 2023, nearly 1 in 5 Americans over 65 were taking one. That’s not surprising-these drugs help. But for many, the hidden dangers are just as real as the benefits. One of the biggest risks? hyponatremia-a drop in blood sodium so low it can cause dizziness, confusion, and falls. And for seniors, a fall isn’t just a stumble. It’s often the start of a hospital stay, a broken hip, or worse.

Why SSRIs Raise the Risk of Low Sodium

SSRIs work by boosting serotonin in the brain. But serotonin doesn’t just affect mood. It also messes with how the kidneys handle water. In older adults, this can trigger something called SIADH-syndrome of inappropriate antidiuretic hormone secretion. Basically, the body starts holding onto too much water. That water dilutes the sodium in your blood. Normal sodium levels are 135-145 mmol/L. When they drop below 135, you have hyponatremia. Below 130? That’s dangerous.

Older adults are especially vulnerable. Their bodies naturally have less water. Their kidneys don’t filter as well. Their hormones don’t respond the same way. Even a small change in fluid balance can push sodium levels into the danger zone. And it doesn’t take long. Studies show hyponatremia often shows up within two to four weeks after starting an SSRI-or after a dose increase.

Who’s Most at Risk?

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

• Those with baseline sodium below 140 mmol/L
• People with a BMI under 25 (especially thin older adults)
• Women-risk is slightly higher than in men
• Anyone taking a thiazide diuretic (like hydrochlorothiazide) at the same time

The combination of SSRIs and thiazides is a red flag. A 2023 Medicare study found that people taking both had a 24-27% higher risk of hyponatremia than those on SSRIs alone. That’s not a small bump. That’s a warning sign.

And not all SSRIs are equal. Fluoxetine carries the highest risk among this class-nearly 3.6 times more likely to cause low sodium than other SSRIs. Venlafaxine, though technically an SNRI, is even riskier. On the flip side, mirtazapine and bupropion have much lower links to hyponatremia. For someone already at risk, switching to one of these might be safer.

The Silent Symptoms That Lead to Falls

Hyponatremia doesn’t always come with nausea or vomiting. In older adults, it often hides. You won’t feel sick. You’ll just feel… off. A little dizzy. A little weak. Your balance feels wrong. Your legs feel heavy. You hesitate before stepping off the curb.

These aren’t just signs of aging. They’re signs of low sodium. And they directly increase fall risk. A 2024 review in the Journal of the American Geriatrics Society found that even mild hyponatremia (130-134 mmol/L) was linked to worse gait stability. That’s why so many seniors on SSRIs end up in the ER after a fall-no one realized their balance was failing because of a lab value, not just old age.

And here’s the cruel twist: up to 40% of people with hyponatremia have no symptoms at all. That’s why checking sodium levels isn’t optional. It’s essential.

What Doctors Should Do-And Often Don’t

Experts agree: before starting an SSRI, get a baseline blood test for sodium. Then check again two weeks later. That’s the standard advice from the Carlat Report and the American College of Physicians. But here’s the problem: many doctors don’t do it.

A 2023 study found that even when hospitals had protocols for sodium monitoring, only about 32% of them actually followed through. Why? Time. Staffing. Lack of reminders. Electronic health records rarely auto-flag high-risk combinations. So unless a doctor remembers to order the test, it doesn’t happen.

And even when it’s caught, it doesn’t always stop bad outcomes. The same study showed that monitoring didn’t reduce hospitalizations for hyponatremia. That doesn’t mean testing is useless. It means we’re missing the next step: what to do after the test.

For mild hyponatremia (125-134 mmol/L), the fix is often simple: stop the SSRI and limit fluids. For severe cases (below 125 mmol/L), hospital care is needed. But correction has to be slow. Rushing sodium back up can cause brain damage from osmotic demyelination. That’s why this isn’t something to handle at home.

Alternatives That Are Safer

If someone’s at high risk for hyponatremia, maybe they shouldn’t start an SSRI at all. There are other options.

• Mirtazapine-no strong link to low sodium. Often used when weight gain isn’t a concern.
• Bupropion-doesn’t affect serotonin much. Good for low energy or lack of motivation.
• Psychotherapy-CBT and other talk therapies work well for late-life depression and have zero physical side effects.

The American Geriatrics Society’s 2023 Beers Criteria even lists SSRIs as potentially inappropriate for older adults with a history of low sodium or fall risk. That’s not a minor note. It’s a hard warning.

And while alternatives exist, access is uneven. Therapy requires transportation, time, and insurance coverage. Many seniors can’t get it. That’s why medication choice matters even more.

What Patients and Families Can Do

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

• Ask: “Has my sodium been checked since I started this medicine?”
• Ask: “Could this drug make me dizzy or unsteady?”
• Track changes: Are you tripping more? Feeling confused after meals? Not wanting to walk? Tell your doctor.
• Review all meds: Are you on a water pill? That combo is risky.
• Don’t cut back fluids unless told to. Dehydration makes things worse.

Many families assume dizziness is just part of getting older. It’s not. It could be a drug. And if it is, fixing it might mean avoiding a broken hip.

What’s Changing in 2025

New tools are coming. In early 2024, the Geriatric Antidepressant Safety Collaborative launched an AI tool that predicts who’s most at risk-based on sodium levels, meds, fall history, and even walking speed from smartwatch data. Hospitals in 127 facilities are already using clinical decision support systems that pop up warnings when SSRIs and diuretics are prescribed together. These tools cut risky prescriptions by nearly 20% in just six months.

The FDA updated SSRI labels in 2022 to make hyponatremia warnings bigger and clearer. Patient guides now include specific language about dizziness and falls. That’s progress.

But the biggest change? Awareness. More geriatricians are talking about this. More pharmacists are flagging interactions. More families are asking questions. That’s what saves lives-not just tests, but conversations.

Bottom Line: Don’t Assume It’s Just Aging

SSRIs help millions of older adults feel better. But they’re not harmless. Low sodium doesn’t come with a siren. It comes with a stumble. A pause before walking. A look of confusion that fades after a blood test.

If you or someone you love is on an SSRI, don’t wait for a fall to happen. Ask for a sodium test. Review all medications. Know the signs. And if dizziness or imbalance starts after starting the drug-don’t brush it off. It might not be aging. It might be the medicine.

The goal isn’t to avoid SSRIs entirely. It’s to use them wisely. With awareness. With checks. With care.