Delayed adverse reactions caused by consecutive injections of different fillers in the same region: Murine skin study

With the introduction of new injectable filler substances and the discontinuation of others, the combination of different types of fillers in a same area is more likely to happen. Naturally, a growing number of concerns regarding the combining of different types of fillers in single area may increase the risk of adverse reactions. Therefore, it has been recommended not to inject a filler in an area previously injected with another type of a filler, especially if that filler is a permanent filler. However, until now, no experimental study has been conducted to estimate the adverse reaction caused by sequential different filler injections.

The aim of this study is to investigate the reactions after consecutive injections of different types of fillers in the same region in in vivo model in order to estimate the safety of the combination method.

We used six healthy rats and three different types of fillers to make single injection or consecutive injections in order to compare adverse reactions.

Histopathology showed a granulomatous reaction in combined filler areas that were identified with different types of micro-implants in the same biopsy.