Should You Test Your Lung Function at Home?

If you have asthma or other problems with your lungs, your doctor usually checks how well you can breathe during every checkup. They probably use a machine that you blow into. It tells your doctor if the main airways in your lungs are open.

If you also do your own lung tests at home, it could help you keep better track of your health. A gadget called a peak flow meter lets you do that. You hold it in your hand and blow into it. You get a reading on how well your breath flows out of your lungs.

Your doctor can say if a home test is right for you. If you have mild asthma, you may not need one. But it could help if your condition is worse. A meter also might be handy if you have chronic bronchitis or emphysema.

What It Does

Both children and adults can use a peak flow meter. If you have asthma, the meter can help you:

  • Track how well your asthma is under control
  • Judge how much your treatment helps
  • Spot a flare-up before it happens so you can act to avoid it
  • Help you decide if you need to call your doctor or go to the emergency room

You may also need a home test if:

  • Your asthma wakes you up at night.
  • Your symptoms get worse during the day.
  • You come down with a cold, flu, or something else that interferes with your breathing.
  • You need to use your emergency inhaler.

How to Use It

You can buy the meter over the counter at a drugstore. There are several types, but they work in pretty much the same way: You blow into the mouthpiece as hard and as fast as you can, and the meter gives you a number that tells how well your lungs are working.

Your doctor can help you choose the meter that’s right for you. Your doctor or your nurse also can make sure that you’ve got the hang of using the meter. When you do, you’ll start by figuring out your personal best reading. That’s the one you get when you feel fine and don’t have symptoms.


To check your best reading, test yourself with the meter every day for 2-3 weeks. Write down your highest number for each day. When you finish the whole series of tests, the highest reading of all is your personal best. It will be your benchmark for knowing how much asthma medicine you need to take from one day to the next.

Your doctor will use your personal best to make a plan for managing your asthma. It will spell out how much medicine you use on a given day, depending on what your meter tells you when you test yourself. The plan will use a system that’s color-coded, like the traffic lights you see when you’re driving.

If you’re doing fine most of the time and your asthma isn’t causing trouble, your doctor may say you don’t need to use the meter every day. Every few days may be enough. But if your asthma acts up, you may need to test yourself several times a day.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on August 28, 2020



Mayo Clinic: “Spirometry,” “Peak flow meter.”

Cleveland Clinic: “Peak flow meter.”

American Lung Association: “Measuring your peak flow rate.”

American Academy of Allergy, Asthma & Immunology: “Peak Flow Meter.”

University of Washington: “New health sensing toll measures lung function over a phone call, from anywhere in the world.”

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