Three ways to manage asthma and allergies. Well, this is kind of a two part question.
I'm assuming that the asthma is triggered by allergies.
So, monitor the pollutants/pollen in the area and if they are high, stay inside.
Make sure that you have your rescue inhaler (Albuterol) or nebulizer with you, at all times. If you're prescribed allergy medication to use daily, use it as directed.
Know your asthma triggers and stay away from them. Make sure your air filter in the house stays changed. In cold weather, stay inside.