Intermediate and long-acting insulins also have ingredients to make them act longer. Today's insulins are very pure without much allergic reactions. Storage and safety Cold insulin injection can be painful. 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.
Do not keep insulin in the freezer or in direct sunlight. Insulin may lose some potency if the bottle has been opened for more than 30 days. Look at the bottle closely to make sure the insulin looks normal. If you use regular, it should be perfectly clear-no floating pieces or color. If you use NPH or lente, it should be cloudy, with no floating pieces or crystals.