I am 62, and hypersensitive to the air pollutants at the big box store where I work. I take allergy shots, advair 2x's day, singular, flonase, have inhalers, ect. But still there is so much drainage down my throat that I can barely speak at times. I don't take allergy pills because it makes the mucas in my throat that much thicker. I wear WoodyKnows nose filters which help me not cough the entire work day, but they don't stop everything. I'm not allowed to wear a mask. The ENT gave me a dosepak of methylprednisolone. How long will the benefits of this medicine last after the script is finished?