Is breo a corticosteroid? and when should you use breo? i use singulair (montelukast). and a nebulizer.

Yes: breo is a steroid/long acting bronchodilator combo medication, prescribed for patients who have asthma/COPD. Whether you should use is a clinical decision based on doctor's judgement of your case, usually medications as Breo are prescribed for initial control of moderate or severe uncontrolled asthma symptoms till control is achieved, then changed to other non combo medications

See below: Do you have asthma or COPD? If so, then Breo is certainly a good option. It does contain a steroid.