The different forms of corticosteroids are useful at treating different allergy and asthma conditions:

• Inhaled forms of corticosteroid are considered by physicians to be the best form of treatment for long–term control of persistent asthma and allergy symptoms. They are taken regularly whether symptoms are present or not to prevent attacks. These may need to be taken for weeks or months before symptoms are completely under control.
  
  
• Corticosteroids by mouth and injection are used to quickly get control over allergy and asthma episodes (e.g., allergic reaction, asthma attack). It is often recommended when high doses of inhaled corticosteroids fail to control symptoms. This type of treatment is usually not suitable for long–term use due to the increased risk of side effects.
  
  
• Nasal and topical corticosteroids are used short–term to relieve minor allergy symptoms. Nasal sprays are useful for treating sinus inflammation, while topical creams can effectively treat rashes on the skin.
  
  
• Some oral corticosteroids are designed to be used for several days to control the recurrence of allergy or asthma episodes. They are discontinued once the individual has recovered or has begun taking another type of regular treatment (e.g., inhaled corticosteroids).