Which Fillers Are Okay to Mix and Which Are Not?

Personally I believe that some products are better for certain applications. Perlane can be used for the lip but it is not ideal for this location. Perlane is a great volumizer but it is difficult to manipulate once placed.
It does not hide well in locations like the lip edge or under eye hollows. For these applications I prefer Restylane. I am not a big fan of Juvederm for certain areas because it seems to drift a bit. However, others seem to love Juvederm. Nevertheless, absolutely these products can be layered into each other without a problem.

Many physicians are finding that good aesthetic results are achieved by inserting thicker products deeper and thinner products more superficially right over the former. Some thinner products can be used in thin skinned areas while the thicker fillers shouldn't. One hestitancy about using multiple fillers, is that if there is a reaction, it might be difficult to discover which filler was responsible for the unwanted effect.

Combining different types of fillers especially on the face is often effective and many times recommended. For example, if you have deep nasolabial folds, then a deeper filler like radiesse or perlane can be placed deeply followed by restylane or juvederm more superficially to improve the folds. In the lips, it is best to use the hyaluronic acid fillers like restylane or juvederm. I think perlane may be too thick and can lump up so you are fortunate it worked well for you. I hope this information helps.

It is perfectly fine to mix fillers (Restylane and Juvederm are both HAs). It is not good to put Radiesse in the lips, but it is great for the cheeks. Good luck.

Although there should be any major problems with combining hyaluronic acid (HA) fillers such as Restylane, Perlane, and Juvederm, there aren't usually any good reasons to do so either. If the goal is to provide volume at a deep level and layer a thinner filler more superficially, then Perlane/Restylane or Juvederm Ultra Plus/Juvederm Ultra would make sense. Technically this is layering rather than mixing.

Great question! Yes, it is safe to use more than one filler in an area, and here at our office we often do. Fillers vary in their consistency, which means some are best suited for certain areas or for certain depths. However, there are times when a combination of fillers gives the best results. 
I've included a video that reviews using more than one filler in a certain area, I hope you find it helpful in your research! 

It is not like mixing drinks! Perlane, restylane, juvederm, etc. are all ok to use together. It should not be a problem. The results should be the same.

It is perfectly safe to mix hyaluronic acid fillers, including Perlane, Restylane, Juvederm, and Prevelle. Fillers of differrent "thickness" are used in different areas of the face for a specific result, and may sometimes be layered on top of one another to achieve the desired effect.
Lips are a special place, and require specific fillers for optimal results (depending on the desired effect... volume, definition, etc.). I find Perlane a bit thick for lip volumization, and prefer Juvederm or Prevelle. However, Perlane is safe. I would not use Radiesse, Sculptra, or other type of non HA filler (except collagen) in the lips however... using these products in the lips is asking for trouble.

Most dermatologists will use different fillers for different locations within the same patient. For instance the lip area may be different than the nasolabial area. The fillers generally do not interact with each other.

It is usually safe to mix different hyaluronic acid fillers, for example, you will do well with either Restylane or Juvederm added to Perlane, if you have a good reason to switch. There are some fillers that should not be used in the lips, like Radiesse or Hydrelle. You should also know that all the fillers that we use in the lips are used off label, meaning that none of them are approved for this use, but they have a long history of being safe and effective.