Could you tell me why we teach not to aspirate after injecting insulin?

My understanding is that it is not necessary to aspirate, although not “wrong” to aspirate. A subcutaneous injection should not result in injection into a big blood vessel. Some bleeding that may occur at the injection site would be from nicking a small capillary.

LM
Additional comments from Dr. Bill Quick:

“Aspirating” (drawing back on the plunger of the needle to check for blood after poking the needle through the skin) doesn’t seem to be necessary. For example, aspirating is impossible with the pen injector devices.

Another reason for not recommending aspirating relates to the possibility of bruising from the inevitable wiggling of the tip of the needle that’s going to occur as you aspirate. Shifting your fingers and/or hands to do the aspirating would seem likely to increase the chance that there will be additional trauma in the skin tissues, causing microbleeding and thus causing visible bruising.

WWQ