SSRI Hyponatremia: Risks, Signs, and What You Need to Know

When you take an SSRI, a class of antidepressants that increase serotonin levels in the brain, commonly prescribed for depression and anxiety. Also known as selective serotonin reuptake inhibitors, these drugs help millions feel better—but they can also cause a dangerous drop in sodium levels called hyponatremia, a condition where blood sodium falls below 135 mmol/L, leading to confusion, seizures, or even coma. This isn’t rare. Studies show up to 1 in 10 older adults on SSRIs develop this side effect, especially in the first few weeks.

SSRIs like sertraline, fluoxetine, and escitalopram trigger hyponatremia by making your kidneys hold onto too much water. Your body’s sodium gets diluted, and your cells swell—especially brain cells. That’s why symptoms often start with headaches, nausea, or feeling off-balance. In older people, it can look like dementia or a stroke. Women and people over 65 are at higher risk. So are those taking diuretics, thyroid meds, or other drugs that affect fluid balance. It’s not about taking too much—it’s about how your body reacts. Even standard doses can cause it.

What’s scary is that many doctors don’t test for it unless symptoms are obvious. If you’ve been on an SSRI for a few weeks and suddenly feel foggy, tired, or nauseous, don’t just blame stress. Ask for a basic blood test to check your sodium. It’s quick, cheap, and can prevent hospitalization. Stopping the SSRI isn’t always the answer—sometimes just cutting back on fluids helps. But if sodium drops too low, you need medical care fast.

There’s a reason we talk about this. The posts below cover real cases, drug interactions, and monitoring strategies that actually matter. You’ll find advice on spotting early signs, understanding which SSRIs carry the highest risk, and how to talk to your doctor without sounding alarmist. We also cover related issues like polypharmacy risks and lab monitoring calendars—because SSRI hyponatremia rarely happens alone. It’s often tangled with other meds, age, or chronic conditions. This isn’t theoretical. People get hospitalized because no one checked their sodium. You don’t have to be one of them.