Does 5-FU Have to Be Mixed with Kenalog to Be Effective?

5-fluorouracil can be quite effective all by itself. It often requires multiple sessions of treatment although a precise interval between sessions has not been established. Also, 5-FU is probably more effective when used very early in the wound healing timeline, but it can be effective months later such as in your case. There's little downside to trying 5-FU by itself, but mixing it with a small amount of Kenalog is fine, too, and may be better for older scars.

All the best,

--DCP

Pearson Facial Plastic Surgery®

5-FU and Kenalog are often mixed and work very well. However, as you pointed out some people are susceptible to atrophy with even small amounts of steroid injection. 5-FU alone typically is effective without that risk of atrophy. It is worth a try to treat your scar as long as you've found a surgeon experienced with 5-FU injection. The other suggestions made by my colleagues are also helpful, massage at this time and possibly revision if you continue to have troubles. I hope this answers your question. 

Stephen Weber MD, FACS

5FU can be injected by itself and it works great for scars. Kenalog is mixed since steroid will decrease any inflammation that may be present or result from any drug injection.