Asthma can vary in severity from person to person.
Intermittent Asthma:
Attacks are brief and not severe.
Symptoms occur on two days or fewer per week.
Asthma night awakenings are two times or fewer per month.
Lung function is generally normal between exacerbations.
Mild Persistent Asthma:
Attacks affect daily activities but are generally not severe.
Symptoms occur more than two days per week but not daily.
Asthma night awakenings are more than two times per month.
Lung function is generally normal between attacks.
Moderate Persistent Asthma:
Attacks affect daily activities and may be severe.
Daily symptoms are common.
Asthma night awakenings are more than once a week.
Lung function is reduced, with FEV1 (forced expiratory volume in one second) between 60% and 80% of the predicted value.
Severe Persistent Asthma:
Attacks limit daily activities, are frequent, and severe.
Symptoms occur throughout the day and frequently at night.
Asthma night awakenings occur often.
Lung function is significantly reduced, with FEV1 less than 60% of the predicted value.