Are there ingredients other than hyaluronic acid in Juvederm/Restalyne?

Hi Rachel; thank your for this interesting question.
Pure hyaluronic acid is reabsorbed in the body within a few days. Cross-linking with proteins give the products specific integrity and various characteristics, depending on the process used.
Juvederm, Restalyne and other hyaluronic acid (HA) manufacturers around the world have added lidocaine to all their products. This has resulted in a more comfortable patient experience. I use filler products with lidocaine added for all of my patients. Fillers remain available for purchase with or without lidocaine. 
There are also non cross-linked hyaluronic acid preparations such as Redensity 1 and Pure. I will often use these products as intra-dermal skin boosters.

Great Question! 
In the Juvederm Family of fillers, all of the products that have an "-XC" after the name have lidocaine mixed in with the hyaluronic acid gel. For example, Juvederm - XC. 
In the Restylane Family, lidocaine is indicated in the name of the product. For example Restylane-L (where the L stands for Lidocaine) or Restylane-Lyft with lidocaine. 
The reason for the lidocaine is to improve comfort during and after injection. In addition, there is also some degree of swelling after injections.  Swelling tends to be associated with increased sensation of pain, so the lidocaine does help with that discomfort. We recommend that you ice the area that was injected to decrease the swelling and hence pain. Sometimes ice is perceived to be uncomfortable, so having lidocaine in the product allows one to ice the area when it is reasonably numb, allowing for less swelling and less pain overall.