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Sudden Heart Failure


Sudden heart failure occurs when heart failure gets worse very quickly. Your heart suddenly cannot pump as much blood as your body needs. Sudden heart failure causes rapid fluid buildup, or congestion, in the lungs and other parts of the body.

Sudden heart failure is an emergency. You need care right away.

Sudden heart failure is also called a "flare-up" or "acute heart failure."

What causes sudden heart failure?

Sudden heart failure can be caused by certain health problems and by some things that you do.

Health problems that can cause sudden heart failure include:

  • Infections, such as pneumonia or a urinary tract infection.
  • Irregular heart rhythms (arrhythmias).
  • Conditions that affect your need for oxygen. These include anemia (not having enough red blood cells) and thyroid problems.
  • Extremely high blood pressure, which can cause fluid buildup in the lungs (pulmonary edema).

Things that you might do that can cause or "trigger" sudden heart failure include:

  • Eating too much sodium.
  • Exercising too hard.
  • Not taking your medicines the right way.
  • Taking medicines that make heart failure symptoms worse.

Not all people are sensitive to or react to the same triggers. What may cause sudden heart failure in one person may not cause any problems for another person.

What are the symptoms?

Symptoms of heart failure start to happen when your heart can't pump enough blood to the rest of your body.

In the early stages of heart failure, you may:

  • Feel tired easily.
  • Be short of breath when you exert yourself.
  • Feel like your heart is pounding or racing (palpitations).
  • Feel weak or dizzy.

As heart failure gets worse, fluid starts to build up in your lungs and other parts of your body. This may cause you to:

  • Feel short of breath even at rest.
  • Have swelling (edema), especially in your legs, ankles, and feet.
  • Gain weight. This may happen over just a day or two, or more slowly.
  • Cough or wheeze, especially when you lie down.
  • Feel bloated or sick to your stomach.

How can you prevent sudden heart failure?

When you have heart failure, taking good care of yourself and following a daily action plan can help you feel better. It can also help you prevent sudden heart failure.

  • Keep the same schedule.

    As much as you can, keep your diet, exercise, and medicine schedules the same every day.

  • Limit sodium.

    Be aware of how much sodium you are consuming. Your doctor can tell you how much sodium is right for you.

  • Take medicines as prescribed.

    Take your medicines at the same time every day. Not taking medicine can cause symptoms to get worse for some people.

  • Know which medicines to avoid.

    Avoid medicines that can make heart failure symptoms worse. Work with your doctor and pharmacist to choose over-the-counter medicines, such as cold medicines and pain relievers, that are safer for you.

  • Be active, but be careful.

    Exercise is good for your heart. But exercising too much or too hard can stress your heart and make symptoms worse. Check with your doctor before you start or change an exercise program. Do not exercise when you don't feel well. Watch for signs that your heart is being stressed, and know when to stop and rest.

  • Keep a healthy lifestyle.
    • Eat heart-healthy foods. These foods include vegetables, fruits, nuts, beans, lean meat, fish, and whole grains.
    • Stay at a weight that's healthy for you. Talk to your doctor if you need help with this.
    • If you smoke, quit.
    • Limit or avoid alcohol. Ask your doctor how much alcohol, if any, is safe for you.
    • Manage other health problems, such as diabetes and high blood pressure.
    • Avoid infections such as COVID-19, colds, and the flu. Get the flu vaccine every year. Get a pneumococcal vaccine shot. If you've had one before, ask your doctor whether you need another dose. Stay up to date on your COVID-19 vaccines.
  • Track your symptoms daily.

    This can help you know when to call your doctor. And it can help you feel more in control of managing your condition.

    • Weigh yourself at the same time each day, in the same clothes. Call your doctor if you notice a sudden weight gain, such as more than 2 to 3 pounds in a day or 5 pounds in a week. (Your doctor may suggest a different range of weight gain.)
    • Write down changes in your symptoms, like shortness of breath or swollen ankles.
    • Take your record of symptoms and weight when you visit your doctor.

Related Information


Current as of: June 24, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.

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