June 1, 2010


Lasix is a water pill used in heart failure patients and as a treatment for high blood-pressure. Many people are prescribed Lasix. In fact, I’m willing to bet you a penny that you know at least one person who is on it. Unfortunately, many people are incorrectly using Lasix.

When I was in medical school at the University of Connecticut, one of my favorite rotations was my surgery experience. At night, on call, and waiting for admissions, I sometimes watched television with the residents — usually if we were not in the mood to study. The television show “ER” was very popular at that time. I remember a question asked on the show: “Is Lasix (furosemide) a once a day medication?” The answer is no. Lasix is a twice a day medication.

Fast forward to today. I’m currently studying for my Kidney recertification exam. One of the study questions asks how to dose Lasix. Surprisingly, most physicians get this one wrong. Most providers prescribe Lasix once a day.

I frequently get consulted for resistant high blood-pressure. The patients I see tend to be on multiple blood pressure medications. One of the first things I do is recommend to my patients that they take their Lasix twice a day. Why is this recommendation necessary? The kidneys are extremely smart organs. When a water pill is given that only lasts for 6 to 12 hours, the kidneys will spend the remaining 12 hours of the day recovering the lost fluid resulting in net zero fluid loss.

The secret to tolerating Lasix is to know what to expect. Be prepared to urinate a lot both during the day and night when you first start Lasix twice daily, or when the dose is increased. After about 4-5 days of using this diuretic, your body will adjust, and you will be less likely to wake up at night to urinate.

So remember, Lasix (furosemide) lasts 6-12 hours and needs to be taken TWICE DAILY in order to work correctly. Ask your doctor if you have any questions regarding Lasix (furosemide).

One Comment
  1. Dr. Van De Graaff

    Good information about this common diuretic. I suppose we should look to the name to remind us of this drug's relatively brief effect (quote from Wikipedia): "The name Lasix is derived from the phrase "lasts six (hours)" — referring to its duration of action." If it were meant to be once daily I suppose the name would have been "La-twenty-four." Dr. VDG

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