A variety of medications can be used to treat seasonal allergic rhinitis, and they all work in slightly different ways. Medications that contain corticosteroids - usually in the form of a nose spray or a pill taken by mouth - help reduce inflammation and the symptoms it causes. Antihistamines are another common medication used to treat seasonal allergic rhinitis. These medications work by blocking the effects of histamine, which is the chemical the immune system releases in response to an allergen. Decongestants may also be taken by mouth or as a nose spray, and these help sinus and nasal symptoms of seasonal allergic rhinitis. Other medications, such as cromolyn and montelukast, work by adjusting the production of certain chemicals in the immune system. Most medications for seasonal allergic rhinitis are available over-the-counter or by prescription, so talk to your doctor about what's best for you.