Is it normal for your injector to mix Kybella with saline? If so, does that make it less effective?

Kybella is made to be injected as is which means that it should not be diluted. It will lessen the efficacy. I would suggest that you see another injector, preferably a board certified plastic surgeon or cosmetic dermatologist. 

Kybella is made of deoxycholic acid, which is what dissolves the fat, removing it from the submental area and jowls permanently. Diluting it with saline would make it less effective and raises the risk of bruising. As others have mentioned, some dermatologists add a bit of lidocaine to make the procedure more comfortable, but not enough to dilute the power of the acid. Please consult a board-certified dermatologist who can show you good results from prior patients treated with Kybella and who does not dilute the formula.

Kybella is injected as is- meaning not diluted. It comes as a liquid in the vial and does not need dilution of any sort.