Controller medicines work on the inside of the airways to prevent inflammation, swelling and mucous inside the airways. These medicines do not work quickly
but take days to start working.  For controller medicines to work, they must be taken every day, even when you are feeling well. There are four types of controller medicines: 

• Inhaled Steroids 
• Leukotriene (lou-ko-try-een) receptor antagonists 
• Long acting bronchodilators
• Combination medicines 

Some people use more than one controller medicine. Your doctor will help you decide which controller medicine is best for you.