Prednisone is a corticosteroid (a medication similar to cortisone or steroid). It works on the immune system to help relieve swelling, redness, itching and allergic reactions. Steroids, medically known as corticosteroids, can reduce inflammation associated with allergies. They prevent and treat nasal congestion, sneezing, and itching and runny nose due to seasonal or year-round allergies.
They can also reduce inflammation and swelling caused by other types of allergic reactions.