there's a lot i had to do... ... watch my diet. stay active. start insulin... today, i learned there's something i don't have to do anymore. my doctor said that with novolog® flexpen, i don't have to use a syringe and a vial... or carry a cooler. flexpen® comes prefilled with fast-acting insulin used to help control high blood sugar when you eat. dial the exact does. inject by pushing a button. no drawing from a vial. you should eat a meal within 5 to 10 minutes after injecting novolog® (insulin aspart [rdna origin] injection). do not use if your blood sugar is too low, or if you are allergic to any of its ingredients. the most common side effect is low blood sugar, which may cause symptoms such as sweating, shakiness, confusion, and headache. severe low blood sugar can be serious and life-threatening. ask your health care provider about alcohol use, operating machinery, or driving. other possible side effects include injection site reactions and low potassium in your blood. tell your health care provider about all medicines you take and all of your medical conditions. get medical help right away if you experience serious allergic reactions such as body rash, trouble with breathing,