What You Need to Know About Lasix (furosemide) and Potassium Levels in Your Body

If you have high blood pressure and/or heart failure, odds are you are taking Lasix (generic name furosemide) for these conditions. Lasix is one of the most commonly prescribed drugs in America. This article will explain how Lasix works, what effect it has on your potassium serum levels, and how you can maintain normal potassium levels in your body while taking Lasix.

How does Lasix work?

Lasix is a diuretic (water pill) that works in the nephrons, the smallest functional unit of your kidneys. Fluid is filtered through your nephrons so your body can absorb the nutrients it needs and excrete waste and excess fluid that will eventually become urine. Lasix works by preventing the re-absorption of sodium and chloride in your nephrons and excreting it with excess fluid instead . Sodium and chloride are two essential electrolytes that can cause high blood pressure when their levels get too high in your body.

What effect does Lasix have on potassium?

In addition to excreting excess sodium and chloride, Lasix also excretes potassium from your body. In fact, Lasix is know to as a 'potassium wasting' drug because of the effect it has on the body's potassium levels. Potassium is one of the body's most important electrolytes, essential for proper cardiac and neuromuscular function. Your normal potassium level should be between 3.5-5.0 mEq/dL. Too little potassium (or hypokalemia) can cause weak irregular pulses, arrhythmias, diminished peripheral pulses, constipation, and orthostatic hypotension (sudden drop in blood pressure when standing up). Too much potassium (or hyperkalemia) can cause confusion, abdominal pain, arrhythmias, low blood pressure, and decreased heart rate. A potassium level of 6.0 mEq/dL or higher is considered toxic.

How do I keep my potassium levels normal while taking Lasix?

If you are taking Lasix, your doctor should have explained to you the importance of keeping safe potassium levels in your body. There are two primary ways of doing this. One is to take a potassium supplement. Some of the more common trade names of potassium supplements include Micro-K and K-Lor. The other way to keep potassium at a safe level in your body is to eat potassium rich foods: cantaloupe, banana, avocado, milk, orange juice, green leafy vegetables, apricots. If you take herbal supplements, keep in mind that licorice can actually increase the potassium wasting effect of Lasix.

If you are taking Lasix (or even you're not) and you are experiencing some of the signs and symptoms regarding potassium levels listed in the 3^rd paragraph, contact your primary care physician right away. You can also talk to your doctor about a potassium sparing diuretic if you feel Lasix is causing too much of a problem with your electrolyte balance.

Sources:

Fluids & Electrolytes-An Incredibly East Pocket Guide, (2006), Lippincott, Williams, and Wilkins, Ambler PA

Schull, Patricia Dwyer, 2010 Nursing Spectrum Drug Handbook - "furosemide", (2010) , McGraw-Hill, USA

The Importance of Potassium for People with Heart Failure, www.americanheart.org