Why are Radiesse injections so painful?

Radiesse is a good filler, but it is thicker than others and so hurts and bruises more. On the other hand, it lasts longer than many fillers and can be injected into the deep tissues.
Discomfort depends on a few variables. One is injector skill. Good injectors know how to inject quickly and with a minimum of pain, no matter what they are injecting. Another is anesthesia. It is nice to do a nerve block with Radiesse. In the marionette lines, that is often difficult. One other technique is to have your injector mix the Radiesse with a bit of lidocaine. Experienced injectors should know how to do this. Ice before and after the injection is also important to prevent pain and bruising.
If you go to someone who is experienced (not the cheap-o guy in the weekly paper), they should discuss all this with you before the injection.