The severity of your
asthma is determined by the intensity and frequency of your symptoms as well as by quantitative measurements of your ability to push air out of your lungs. The process of measuring this ability, known as peak expiratory flow (PEF), is called peak flow monitoring. There are four levels of increasing severity:
- Intermittent: This is the least serious level of asthma. At this level, a person has
asthma symptoms no more than once a week and will not be awakened at night with asthma symptoms more than twice a month. An asthma attack may last from a few hours to a few days. A person at this level will not have symptoms between asthma attacks, and between attacks the peak expiratory flow rate is normal, which
means the PEF reading will vary by less than 20 percent.
- Mild persistent: At this level, a person has asthma symptoms more than two times a week but not every day. Nighttime asthma symptoms occur more than twice a month but less than once a week. When it occurs, an asthma attack may slow daily activities. The PEF reading will vary by 20 percent to 30 percent.
- Moderate persistent: At this level, a person has asthma symptoms daily and will use a short-acting inhaled asthma medicine every day. Nighttime symptoms occur about once a week. Asthma attacks may happen at least twice a week and last for many days. At this level, asthma attacks get in the way of daily
activities. The PEF reading may vary by more than 30 percent.
- Severe persistent: This is the most serious level of asthma. At this level, a person has asthma symptoms all the time, limiting the sufferer's activity. Asthma attacks are common, as are nighttime symptoms. The PEF reading may vary by more than 30 percent.
