How Long Does Juvederm Last?

Good question, but the answer can be very technical. The value or longevity of a Hyaluronic Acid filler (HA) is determined by the amount of cross-linking of the gel molecules. The body is very effective at removing things that do not belong. The beauty of HA is that it is also produced in the body so that it can stay because it is not a completely foreign object. Collagen that used to be injected was from cow hide so that it was rapidly identified and then broken down by the body. It also required a test to determine if you had an allergy.
HA is not broken down by this pathway, it is broken down other ways. The more solidly (or crosslinked) a HA product is the longer it will last. The absolute amount of HA in a syringe does not translate into more product remaining in an injected area. ONLY the crosslinked amount of HA in the syringe will actually remain. The non-crosslinked product will be disolved in a few days. The non-crosslinked HA is smoother and allows for easier injection and some controllability in some hands but will NOT contribute to longevity.
Restylane is a higher concentration of cross-linked molecules of HA than Juvederm. So Restylane is stiffer, requires more skill to inject correctly, more skill to place correctly and will last longer. In some areas these are desirable consequences like the nasolabial folds. Juvederm is softer and easier to inject and feels different so it is better in the lips but it will go away faster.
Juvederm in lips? 4- 6 months?
Restylane in lips? 5-6 months?
in face? can last over a year - both products
Nasolabial folds? 6 months and up depending on injector.
I hope this helps.

Every patient is different. It really depends on the area injected, how much product injected, and how quickly your body metabolizes the product.  On average in our practice, Juvederm Ultra can last anywhere from 6-12 months. The lip area can last on average about 4-6 months. The tear trough and nasolabial folds on average can last around 9-12 months. 

That is a really good question that has a rather complicated answer.
There are a number of factors at work in determining how long an HA filler (such as Juvederm) will last.  Longevity is influenced by:  the amount of cross-linking in a particular product (ie Vollure has more cross-linking, and, therefore more stability than Juvederm Ultra or Ultra Plus).

Duration of effect also depends on the patient's metabolism (how quickly the is body breaking down the product), and where the product was placed ( eg. our lips are in constant motion and mechanically break down HA fillers more quickly than in an area with less movement - such as tear troughs).  Additionally, products have more longevity and stability with additional treatments to an area.  

The experience and skill of the injector is critically important for proper placement and for achieving your best aesthetic result.  The injectors in our plastic surgery office have extensive and ongoing education and training in the latest and safest techniques to successfully accomplish a beautiful, natural look.