Since you want the inflammation when doing Kybella, is it a bad idea to take arnica that brings down the inflammation/swelling?

That is a great question. The honest answer is no one knows, because the studies haven't been done.  Many physicians (myself included) recommend Ibuprofen after the injections to help with discomfort, and that could also potentially decrease inflammation.  But my best guess is that is should be fine.  The local effect of the deoxycholate on the fat cell is probably not going to be influenced much by the Arnica and the inflammation is most likely a byproduct of the reaction and not the main effect.  You might try ZYRTEC( Ceterizine) which is a non sedating antihistamine with one pill the day before, the day of and the day after your injection.  My patients seem to think this helps limit the swelling with KYBELLA

Hi Chloe, it is perfectly safe to take Arnica after your procedure. Although it's used more for bruising purposes some say it can help with swelling as well and shouldn't have any kind of negative effect with your Kybella. Happy healing, Best. Dr. Emer 

Thank you for your question about Kybella.I do not think that the use of arnica montana or bromelain pineapple extract would diminish the results of your Kybella treatment.  This particular combination, however, has not been rigorously studied.
To be sure what is best for you, see two or more experienced,
licensed and board-certified providers in your area for a complete evaluation
to make sure you are a good candidate and that it is safe for you to have
treatment.
I hope this helps.