Allergies can cause swelling and inflammation of the tissues in the nose. This can cause nasal congestion and difficulty inhaling. Usually antihistamine decongestants are used to treat nasal congestion. However, in severe cases, these may not work efficiently. In such cases, a doctor may prescribe cortisteroids. These substances are highly potent and cause side effects. They are not available over the counter. Doctors prescribe these medicines for people when they feel that their symptoms are severe and need to be controlled quickly.

Cortisteroids are available in the form of intranasal sprays, injections, inhalers, pills, eye drops etc. Intranasal cortisteroid sprays are commonly used and are relatively safe because their effect is limited to the tissues of the nose and there are no harmful side effects. Pills and injections are used only as the last resort. They cannot be used for more than a few days because they cause side effects like             increased blood pressure, bruising, bone loss, weight gain, worsens diabetes and glaucoma and slows down growth in children.

Cortisteroids reduce swelling and inflammation by vasoconstriction. They also prevent immune system cells like mast cells and macrophages from migrating to the affected area. In this way, it reduces inflammation, swelling and other allergy symptoms.