My 15 year old daughter has asthma that I have trouble controlling it. Any suggestions?

15yo should B respon. Asthma control can be an issue of medications, events or compliance. Teens often have more compliance problems out of a sense of "why me" or presumed invulnerability. By 15 responsibility for maintaining control should be theirs. They need to figure out a good daily routine that incorporates preventive and rescue meds & be willing to stick with it or ask their doc to fine tune the process.
Control. I agree with dr. Ferguson that the teens are often a difficult time. Your doctor can help give your teen more control, and better control, by discussing and giving you both an asthma action plan, with a peak flow meter to get more objective data on how their asthma is doing. I would not rely on air purifiers etc although environmental control can sometimes help.? Any smoking around them?
Add maintenance meds. If your daughter is only on a rescue inhaler (e.g. Albuterol) then add inhaled corticosteroid to treat inflammation; if on inhaled corticosteroid, add long acting beta agonist (laba) to relax bronchial muscles and open airways; if on inhaled corticosteroid and laba, increase dose of corticosteroid. You should be working closely with an md skilled in asthma management.
Fresh air Tech. Asthma is due mostly to allergy. Airborne, like dust, pollen, molds, etc. And food also. The best is the use of fresh air tchnology that eliminates all the airborne contaminants inside the house. Log in to www. Drernie. Co.Cc and click on fresh air tech. Control is the key word you asked and I must add prevention of recurrence. My patients can't attest to thi by the way.