Results

Once you and your doctor have established your peak flow zones, you'll use a color-coded system based on your symptoms and your peak flow. This system tells you what to do when you are in each zone.

Green, yellow and red: Understanding your peak flow zones

Your doctor will use your personal best to set your peak flow zones. Each zone is determined by your peak flow rate and symptoms. The color code for each zone reflects progressively more-severe symptoms:

Green zone = stable

• Your peak flow rate is 80% to 100% of your personal best, an indication that your asthma is under control.
• You probably have no asthma signs or symptoms.
• Take your preventive medications as usual.
• If you consistently stay within the green zone, your doctor may recommend reducing your asthma medication.

Yellow zone = caution

• Your peak flow rate is 50% to 80% of your personal best, an indication that your asthma is getting worse.
• You may have signs and symptoms such as coughing, wheezing or chest tightness — but your peak flow rates may decrease before symptoms appear.
• You may need to increase or change your asthma medication.

Red zone = danger

• Your peak flow rate is less than 50% of your personal best, an indication of a medical emergency.
• You may have severe coughing, wheezing and shortness of breath. Stop whatever you're doing and use a bronchodilator or other medication to open your airways.
• Your asthma action plan will help you decide whether to call your doctor, take an oral corticosteroid or seek emergency care.

Peak flow: Just one tool for asthma control

Using a peak flow meter can be an effective tool for managing your asthma — but there are other things you need to do:

• Use an asthma action plan. An action plan is a simple but important part of managing your asthma. It helps you keep track of which medications to take, when to take them and what doses you need, based on whether you're in your green, yellow or red zone.
• Meet with your doctor. Even if your asthma's under control, meet with your doctor on a regular basis to review your action plan and revise it as needed. Asthma symptoms change over time, which means your treatment may need to change, too.
• Avoid your triggers. Pay attention to things that trigger your asthma symptoms or make them worse, and try to avoid them.
• Make healthy choices. Taking steps to stay healthy — for example, maintaining a healthy weight, getting regular exercise and not smoking — can make a big difference in reducing your asthma symptoms.