Diuretics: What they do and how to use them safely

Diuretics, often called "water pills," help your body get rid of extra salt and water through urine. Doctors prescribe them for high blood pressure, heart failure, swelling (edema), certain kidney problems, and cirrhosis. They work fast and can make a big difference, but they also change your body's electrolytes, so you need to understand the basics.

How diuretics work and the main types

There are three common groups you’ll see:

- Loop diuretics (furosemide, bumetanide): Very strong. Used for heart failure or large fluid build-up. They remove lots of water but can drop potassium and magnesium.

- Thiazide diuretics (hydrochlorothiazide, indapamide): Often used for blood pressure. They work steadily and can lower potassium over time and raise blood sugar or uric acid in some people.

- Potassium-sparing diuretics (spironolactone, amiloride, eplerenone): Weaker at removing water but help keep potassium from dropping. Spironolactone also affects hormones, which matters when it's used for acne or hormonal issues.

Practical safety tips you can use today

Take them in the morning—diuretics make you pee, so you don’t want to wake up at night. If you’re on a diuretic that lowers potassium (loops or thiazides), eat potassium-rich foods like bananas, oranges, potatoes, and spinach unless your doctor says otherwise. If you’re on a potassium-sparing drug, don’t add extra potassium or use salt substitutes without checking with your provider.

Watch for symptoms: dizziness, lightheadedness when standing up, muscle cramps, weakness, or an irregular heartbeat. These can mean your electrolytes or blood pressure are off. Check with your doctor if you notice any of these signs.

Labs matter. Your doctor will usually want blood tests—electrolytes and kidney function—within a week or two after starting or changing dose. Bring a list of all medications you take. NSAIDs (like ibuprofen), ACE inhibitors, ARBs, and lithium can interact with diuretics and change kidney function or potassium levels.

Travel and activity: If you’re flying or on a long drive, plan bathroom breaks and stay hydrated. Diuretics don’t mean "drink less"—they change fluid balance, so follow your doctor’s guidance on fluids, especially if you have heart failure.

Pregnancy and breastfeeding need special attention. Some diuretics aren’t recommended in pregnancy. If you’re pregnant, planning pregnancy, or breastfeeding, talk to your clinician before using any diuretic.

Don’t stop suddenly without asking your doctor. Stopping diuretics abruptly can worsen swelling or blood pressure control. If side effects are a problem, there are usually alternative drugs or dose changes your doctor can try.

Diuretics are powerful and useful when used right. Know the type you’re on, watch for symptoms, keep up with lab checks, and talk to your provider about food, other meds, and travel plans. That keeps the benefits high and the risks low.