An asthma action plan is a written plan of what to do if you have an asthma attack. You are in the red zone of your asthma action plan if you have severe asthma symptoms. Symptoms include:

• Peak expiratory flow less than 50% of your personal best measurement. To find 50% of your personal best, multiply your personal best measurement by 0.50. For example, if your personal best flow is 400, then 50% of that is 400 times 0.50, which is 200.
• Any shortness of breath while walking, talking, or at rest.
• Use of the chest muscles to breathe. The skin between, above, and under the ribs collapses inward with each breath (retractions).
• Wheezing. But if symptoms are very severe, you may not hear any wheezing. Wheezing will stop when the amount of air moving through the bronchial tubes becomes dangerously low. In this case, no wheezing is actually worse than hearing wheezing.

Treatment for asthma attacks in the red zone includes:

• Seeking immediate medical attention while you are following your asthma action plan.
• Using medication based on your asthma action plan.
• Talking with a health professional immediately about what to do next. This is especially important if your peak expiratory flow does not return to the green zone or stays within the yellow zone.