Leukotriene modifiers are primarily used in the treatment of asthma for the purpose of preventing asthma attacks. The drugs may be used in combination with other therapies. Some types may also be used in the prevention of allergic reactions for non-asthmatics.

Asthma-related conditions for which leukotriene modifiers may be prescribed include:

• Moderate persistent asthma. Symptoms occurring once each day and more than one night a week.
  
  
• Mild persistent asthma. Symptoms occurring more than two times a week during the day and more than two times each month at night.

Physicians are still determining which patients are most likely to benefit from the use of leukotriene modifiers. However, these medications appear to be particularly effective in patients who suffer from aspirin-sensitive asthma, a condition in which a patient suffers a severe asthma attack after taking aspirin. Leukotriene modifiers also have been effective in patients whose asthma is triggered by exercise or allergies. There is some evidence that leukotriene modifiers may be effective in treating cases of severe adult asthma.

Leukotriene modifiers are designed to be taken daily to prevent asthma attacks before they occur. They are not bronchodilators and should not be used to treat asthma attacks once they have begun. Those who are unable to control asthma symptoms without increasing their dosage from the prescribed amount should contact their physician immediately, as this may indicate an impending asthma attack.

Some leukotriene modifiers have been approved in the United States to prevent the itching, sneezing and nasal congestion associated with seasonal and perennial (year-round) hay fever (allergic rhinitis). Some studies have indicated that leukotriene modifiers may be more effective when combined with antihistamines, thereby shutting down two major chemicals in airway constriction, histamines and leukotrienes.

It should be noted that leukotriene modifiers have not been found to be as effective as inhaled corticosteroids, and that there is not yet a body of evidence to conclusively state that leukotriene modifiers are an effective means of treating allergic rhinitis by themselves.

Other conditions for which leukotriene modifiers may be prescribed include:

• Respiratory syncytial virus (RSV), the chief cause of lower respiratory tract infections in children. Leukotriene modifiers may help by blocking the leukotrienes that act as mediators in the lingering wheezing and other asthma-like symptoms that follow a bout of RSV.
  
  
• Hives (red, swollen patches of skin). Leukotriene modifiers may be used for some patients with chronic, difficult-to-treat hives.
  
  

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