Prednisone has been specially designed for patients diagnosed with low corticosteroid levels and works by replacing the steroids that are not produced in sufficient quantities by the body. This drug is efficient for a wide range of conditions that may affect your skin, eyes, lungs, intestines, blood, kidneys, thyroid and stomach. It also alters the way your immune system works. Also report any herbal products you are taking at the moment, especially St. John's wort. When taking prednisone, try to avoid drinking grapefruit juice and talk to your health care provider about your diet. Of course, your health care provider may provide recommendations that are slightly different, so make sure you follow those as they are based on the assessment of your current health condition.