My husband got a cortisone injection in his left knee 3 days ago.  On the day of the injection, about 6 hours later, he c/o rapid heart beat and dizziness.  I counted his pulse, 100, and took his BP, 160/90. I took him to the emergency room and the MD performed an EKG, took blood, and did vitals.  The MD said that his potassium was low.  He gave him potassium chloride by mouth and had NS IV. His heart rate came down. My husband c/o of feeling faint. The MD put him in trendelenburg position. My husband started to feel better.  After another hour of observation, he was discharged.  My husband now complains of "hot flashes" and sometimes feels jittery.  I have researched the potassium chloride prescription (since I am a nursing student) and noticed that the dosage of 20 mEq once a day is a low dose. I learned that cortisone has some adverse reactions of restlessness, confusion, and hypertension.  How long do the adverse reactions to cortisone last?