Never did it Sub-q only IM. But I have done Kynoselen Sub-q and it caused Major bruising that permanently stayed with me from over 8 years ago. Granted Kyno has other stuff in it besides B-12. Not sure why this happened but it pissed me off something fierce. Kyno is a great product. Better than B-12 alone IMHO. Doing it IM is a real pain in the ass though...especially if your already doing other things daily IM. Just make sure it human grade if possible like chemicalneed's site has. I found a site that has a complete B-complex injectable. They offer the B-complex which is(B-1,2,3,5,6), B-1,B-6,B-9, And B-12 individually as injections along with Injectable Vitamin-C. I am in no way connected to them. Its a site I found while looking and Thought about trying before. If anybody wants the address pm me. Also have sites for Kyno and HEMO-15 too!.