Kenalog injections, can it make your nose smaller?

After rhinoplasty, there is always some degree of tissue swelling during the healing process. To help reduce swelling, conservative low-concentration steroid injections can help expedite resolution if the swelling is felt to be greater than desired.  When injected in the appropriate manner, they can be very useful if there is significant swelling of the nose post-operatively.  But as one of the other surgeons indicated in an answer to your question, one must be careful to inject a lower concentration and into the appropriate tissue plane to help avoid the risk of tissue atrophy and irregularities after injection.  If you have any questions or concerns regarding your nose after the injection, I would contact your surgeon.  

Kenalog can be dangerous for healthy tissue. You shouldn't use it for nose reduction. 
I hope this was helpful,Dr. Daniel BarrettPlastic SurgeonBeverly Hills, CA

Cortisone injections are unwise in the nose! never repeat that! they destroy tissues, shrink, make atrophies and if used in such early stage are very very dangerous.

 The purpose of  cortisone injections placed in the nasal tip is to reduce the amount of swelling in the skin, not the cartilage. Injecting steroids into this cartilage will have no benefit. They help control and modulate the soft tissue envelope (the skin) over the bony and cartilaginous framework of the nose throughout the healing process for the first six months.