Be sure that the syringe you use matches the insulin strength. In Europe and Latin America, U-40 insulin is also used. If you're outside the United States, be certain to match your insulin strength with the correct size syringe. All insulins have added ingredients to keep them fresh and help them work better. Today's insulins are very pure.
Allergic reactions are rare.
Storage and safety. Using cold insulin can make your shot more painful. You can keep the bottle of insulin you are currently using at room temperature or warm the bottle by gently rolling it between your hands before you fill the syringe. If you buy more than one bottle of insulin at a time, store the extra bottles in the refrigerator until you start to use them. Extreme temperatures destroy insulin.