Inform your physician of all the medications you take (prescription and over the counter) and other medical conditions you have before taking a Medrol Dose Pack. If you are scheduled for surgery, the medical staff must be aware that you are on a Medrol Dose Pack. It never should be taken if you are allergic to methylprednisolone or have a fungal infection. Since steroids can weaken the immune system, avoid people who have colds and the flu. Contact your physician if you become exposed to the measles or chicken pox, as these illnesses can become serious when a person is on steroid medication.