Dehydration and Lithium: Risks, Symptoms, and What You Need to Know

When you take lithium, a mood-stabilizing medication commonly used for bipolar disorder. Also known as lithium carbonate, it works by balancing brain chemicals—but it has a very narrow safety window. Even a small drop in your body’s water levels can cause lithium to build up to toxic levels. This isn’t theoretical—it’s a real, documented risk that sends people to the ER every year.

Dehydration, a condition where your body loses more fluids than it takes in. Also known as fluid deficit, it’s not just about feeling thirsty. Sweat, diarrhea, vomiting, or even just drinking less water on a hot day can trigger it. And when that happens while you’re on lithium, your kidneys can’t flush out the drug the way they should. That’s because lithium is cleared through your kidneys, and they need enough sodium and water to do their job. Low sodium? Low fluids? That’s a red flag. Studies show lithium toxicity is 3 to 5 times more likely in people who become dehydrated, especially older adults or those on diuretics like furosemide, a water pill often prescribed for heart failure or swelling. You don’t need to be bedridden to be at risk—just skip a few glasses of water after a workout, or forget to drink while sick, and you could be in trouble.

Symptoms of lithium toxicity aren’t subtle. You might feel shaky, dizzy, or nauseous. Your hands might tremble. You could get confused, have trouble speaking, or even experience seizures. These aren’t "side effects"—they’re warning signs your body can’t handle the lithium level in your blood. If you’re on lithium, you need to treat hydration like part of your daily medication routine. Drink water regularly, don’t cut back on salt unless your doctor says so, and watch for signs of illness that could lead to fluid loss. Your blood tests (like lithium levels and kidney function) matter, but your daily habits matter more.

Some of the posts below dive into how medications like lithium interact with other drugs and body systems. You’ll find guides on diuretics, kidney health, and how to spot early signs of trouble before it becomes an emergency. Whether you’re taking lithium yourself or helping someone who is, this collection gives you the practical, no-fluff facts you need to stay safe.