I couldn't find much stating it is necessary or helpful to change needles between drawing up and injecting. Found one saying it may help. Personally, I doubt it would be any more painful as the stopper is not going to dull the needle enough to cause more discomfort. Certainly, I check it first, but do not generally change the needle. Technique is most important with an injection; poor technique is more likely the reason for a painful injection. I know of diabetics who reuse insulin needles (questionable practice, I know, but it's the cost factor) and dullness is not an issue.
Changing Needles - if the integrity or sharpness of the needle is in question it should be changed otherwise no reason to do so. To change the needle after drawing up may also be an advisory in the product monograph.
Is it recommended to change needles after a vaccine dose has been drawn into a syringe? No. Also, it is unnecessary to change the needle if it has passed through two stoppers, which is done when a lyophilized vaccine is reconstituted. Changing needles is a waste of resources and increases the risk of needlestick injury. (4/03)
The needle gauge is not important to the shot, but it may be important for pain. The larger number, the smaller the needle. (A 27-gauge needle is smaller than a 22 gauge.) If you use a different needle for drawing the
medications and shooting, it may help, too.
CONCLUSION: Changing the needle before the administration of subcutaneous heparin did not decrease the size of ecchymoses as compared with the size to the size of ecchymoses when the investigator did not change the needle.
Traditionally nurses have used one of two drawing up techniques for the administration of intramuscular (IM) injections. In the first, the injectable is drawn up using one needle, which is then discarded before administration using a new needle. Alternatively, the injectable is drawn up and administered without changing the needle. Advocates of the two-needle technique suggest that this method reduces pain at the injection site. In the present study, 70 subjects completed an independently validated pain scale following administration of an IM depot neuroleptic. The conclusion, that there is a significant reduction in injection site pain, using the two-needle technique, is not supported by the data obtained in this study.