Older Adults on SSRIs: How to Prevent Hyponatremia and Falls

Every year, hundreds of thousands of older adults start taking SSRIs to manage depression or anxiety. These medications help many people feel better-but for some, they come with hidden dangers. The biggest risks? Low sodium in the blood-called hyponatremia-and the falls that often follow. These aren’t rare side effects. They’re common, serious, and often preventable.

Why SSRIs Are Risky for Older Adults

SSRIs like sertraline, fluoxetine, and escitalopram are widely prescribed because they’re generally safer than older antidepressants. But for people over 65, the body changes in ways that make these drugs more dangerous. As we age, our kidneys don’t filter blood as well. We have less total body water. Our hormones, especially antidiuretic hormone (ADH), start acting differently. All of this sets the stage for hyponatremia.

SSRIs cause the body to hold onto too much water. This dilutes the sodium in your blood. Normal sodium levels are between 135 and 145 mmol/L. When they drop below 135, you have hyponatremia. In older adults, this happens in nearly 6 out of every 100 people taking SSRIs. That’s a 2.2 times higher risk than those not taking these drugs.

Fluoxetine carries the highest risk among SSRIs. Studies show it causes hyponatremia in about 6.5% of older users. Even more concerning: many people don’t feel sick at first. There’s no sharp pain or obvious sign. Instead, symptoms creep in quietly-dizziness, weakness, confusion, or trouble walking. These aren’t just ‘getting older’ symptoms. They’re warning signs of low sodium.

The Fall Connection

When sodium drops, so does balance. Dizziness and gait instability are the most common early signs. For an older adult, that’s not just uncomfortable-it’s dangerous. A stumble can turn into a broken hip, a hospital stay, or worse. While no study has directly measured how many falls are caused by SSRI-induced hyponatremia, the link is clear in clinical practice.

Geriatricians see it all the time: a patient falls, gets admitted, and only then is their sodium level checked. It’s low. They’re put on fluids, the SSRI is stopped, and they improve. But by then, the damage is done. One fall increases the chance of another by 50%. And each fall raises the risk of long-term disability or death.

Who’s at Highest Risk?

Not every older adult on an SSRI will develop hyponatremia. But some are far more vulnerable:

• Those with baseline sodium below 140 mmol/L
• People with low body weight (BMI under 25)
• Women, especially post-menopausal
• Anyone taking thiazide diuretics (like hydrochlorothiazide) at the same time

The combination of an SSRI and a thiazide diuretic is especially dangerous. Together, they increase hyponatremia risk by over 20%. That’s not a small interaction-it’s a red flag. Yet, many prescribers still pair them without checking sodium levels first.

What Should Be Done Before Starting an SSRI?

The best time to catch hyponatremia is before it starts. Here’s what works:

1. Get a baseline blood test for sodium before starting any SSRI.
2. Repeat the test two weeks after starting-or after any dose increase.
3. Review all medications. If the patient is on a thiazide diuretic, consider switching to a different blood pressure pill, like an ACE inhibitor or calcium channel blocker.
4. Ask about recent falls or unexplained dizziness. These are clues, not just accidents.

Some clinics have started using electronic alerts. When a doctor prescribes an SSRI to someone over 65 who’s also on a diuretic, the system pops up a warning: “Check sodium in 14 days.” Hospitals like Johns Hopkins Bayview found that using these alerts cut emergency visits for hyponatremia by 22% in just six months.

What If Sodium Is Low?

If sodium is below 135 mmol/L, don’t panic-but don’t ignore it either.

• Mild hyponatremia (125-134 mmol/L): Stop the SSRI. Limit fluids to under 1.5 liters per day. Recheck sodium in 3-5 days. Most people bounce back.
• Severe hyponatremia (below 125 mmol/L): This is a medical emergency. Hospitalization is needed. Sodium must be corrected slowly-too fast can cause brain damage.

Many doctors hesitate to stop antidepressants because they worry about relapse. But if the patient is dizzy, weak, or falling, the SSRI is doing more harm than good. In these cases, switching to a safer alternative is the right move.

Alternative Antidepressants with Lower Risk

Not all antidepressants carry the same risk. Some are much safer for older adults:

• Mirtazapine: This is the safest option. It doesn’t affect ADH or sodium levels. It can even help with sleep and appetite, which many older adults struggle with.
• Bupropion: Another low-risk choice. It doesn’t cause hyponatremia. It may not help with anxiety as well as SSRIs, but it’s a solid option for depression.
• Psychotherapy: Cognitive behavioral therapy (CBT) works just as well as medication for mild to moderate depression in older adults-and has zero side effects.

The American Geriatrics Society’s 2023 Beers Criteria now lists SSRIs as potentially inappropriate for older adults with low sodium or risk factors for it. That’s not a small warning. It’s a call to change practice.

The Monitoring Paradox

Here’s the frustrating part: Studies show that checking sodium levels doesn’t always prevent hospitalizations. One 2023 study found that even when doctors followed guidelines and tested sodium, patients still ended up in the hospital. Why?

Because testing alone isn’t enough. You need action. If the sodium is low, you must stop the drug or switch it. You must educate the patient and family. You must watch for falls. Many clinics test-but then do nothing. That’s why monitoring fails.

The real solution isn’t just more blood tests. It’s better systems: clear protocols, patient education, and fast follow-up. One geriatric practice in Florida started giving patients a simple handout: “If you feel dizzy, weak, or confused after starting this pill, call us immediately. Don’t wait.” They cut their fall-related ER visits by 30% in a year.

What You Can Do Right Now

If you or someone you care for is on an SSRI:

• Ask the doctor: “Has my sodium been checked since I started this medicine?”
• Ask: “Is there a safer alternative, especially if I’ve had falls or feel unsteady?”
• Watch for dizziness, confusion, or trouble walking. Don’t brush it off as ‘just aging.’
• If you’re on a water pill (hydrochlorothiazide, chlorthalidone), ask if it’s still needed.
• Keep a list of all medications-including over-the-counter ones-and review it every 3 months.

Depression is real. It’s painful. But treating it shouldn’t come at the cost of safety. The goal isn’t just to feel better-it’s to live well, stay strong, and avoid preventable harm.

What’s Changing in 2025

New tools are emerging. A national initiative called the Geriatric Antidepressant Safety Collaborative is now using AI to predict who’s most at risk. It looks at sodium levels, fall history, medication lists, and even walking speed. Early results show it can flag high-risk patients with 85% accuracy.

The FDA has also updated SSRI labels to include stronger warnings for older adults. Pharmacies now have to give out new patient guides that clearly state the risk of low sodium and falls.

But the biggest change? More doctors are listening. The tide is turning away from automatic SSRI prescriptions for older adults. Safer options are getting more attention. And patients are asking better questions.

Final Thoughts

SSRIs aren’t bad drugs. They help millions. But in older adults, they need careful handling. The risk of hyponatremia and falls isn’t theoretical-it’s documented, measurable, and preventable. The solution isn’t avoiding antidepressants altogether. It’s choosing wisely, monitoring closely, and listening to the body’s quiet warnings. A simple blood test, a conversation about falls, and a switch to a safer medication can make all the difference between staying independent and ending up in the hospital.