We have used the 23ga needed before to administer the Solu-Cortef and it worked great. I know it may look big to you, but be careful about going to a smaller needle without first checking with the pharmacist or the manufacturer. Once the manufacturer of another medication my daughter takes changed to a smaller needle in an effort to make injection less painful for children and they ended up with a needle that was too small for the medication to easily flow through. They had only gone down one size. We ended up having to go out and buy the proper size needle ourselves. When I called the company to complain about it they said they knew it was a problem, but the kits had already been made up and they would have to use those before the needle size could be changed back. I know that when we tried the smaller needle it ended up more painful because the medicine did not flow properly. I know we all want to make these shots as painless as possible for our children and it is imperative we use the correct size needle.