The sources separate two things: the fat cells Kybella treats, and the results you see over time. Keep them apart when a provider sells you the word permanent.

What is permanent

Cleveland Clinic says Kybella causes a reaction in your fat cells, permanently destroying them and leading to results that last a long time.

What the timeline looks like

North Dallas Dermatology says results of the Kybella treatment can be observed in a period of four to six weeks and the effects of the treatment can last for years.

Reading the gap between the two

One source describes the cells as permanently destroyed. The other describes effects that can last for years, which is a period and not a promise of forever. A provider who guarantees a lifetime result is going further than either source does.

Ask what follow-up they expect and what a touch-up visit would cost, because that is the part a Folsom budget has to cover if the result does not hold the way you hoped.

Further reading

Start with the American Society for Dermatologic Surgery skin treatments page on Kybella, then North Dallas Dermatology on five things to know about Kybella. Cleveland Clinic also publishes a Kybella cosmetic injection overview.