How long do they keep the remaining half of the syringe when lip injections are done?

Revampy,
Each office and physician will have a slightly different view on this issue.  Most offices I am familiar with will preserve  the remainder of a unused syringe for their patients for small touch ups a few weeks later (final results of fillers typically take around 2 weeks in the lips).  Some will keep the syringe refrigerated until the expiration date.  It is best to check with your specific physician for their policy.  Cheers - Dr. Nesiba

We typically use the entire syringe but, if the occasion arises where we need to keep some for a possible touch up, it is kept until the expiration date.

Each office will have their own policy. I recommend following up with your Doctor about their office's policy. It takes 1-2 weeks for final results. Best, Dr. Emer

We
do not "save syringes." Patient
safety is a primary concern. The syringes
are labeled single use only.
FDA’s
statement: injectable gel is packaged for
single patient use. The contents of the syringe are sterile and non-pyrogenic.
Do not re-sterilize. Do not use if the package
is opened or damaged. As with all transcutaneous procedures, dermal filler
implantation carries a risk of infection. Follow standard precautions
associated with injectable materials.
FDA’s
statement: injectable gel is to be used
as supplied. Modification or use of the product outside the Directions for Use
may adversely impact the sterility, homogeneity, and performance of the product.
The
training and safety measures are of the utmost importance. Choose a Board
Certified Plastic surgeon, Board Certified Dermatologist, Board Certified
Facial Plastic Surgeon, Oculoplastic surgeon, or Certified Aesthetic Nurse
Specialist.
Ask questions!!

There really is no official answer on this.  It depends upon the comfort level of the injector as to how long to save opened syringes.  I do not like to save them for more than 8 weeks.

There are no hard an fast rules regarding how long to store a syringe of product after it has been opened, and it is left up to the discretion of the practice. The risk/benefit questions that each practice has to balance when determining their policy is the risk of contamination of the product with bacteria, fungi, etc. once opened (which is generally speaking very, very low) versus the benefit the patient receives from being able to have access to the remaining product after injection for touch ups. Each practice is going to come up with their own answer to this balance based on what they believe is right for their patients (safety versus convenience). My recommendation would be to schedule your injections so that the initial and the touch-up sessions fall in the window that your injector's practice deems safe so that you don't have to unnecessarily waste any product. I hope this helped, good luck!!  

Different providers have different policies on keeping the fillers. Some providers do partial syringes with patients while others will "bank" the leftovers for another visit. This could be anywhere from a couple weeks to the expiration date listed on the syringe. You should call your surgeon and ask about the office policy. 

Hi revampy,Each office is different as to if they save syringes or not, and how long they will hold the product. I would recommend calling your providers office to determine how long they will hold on to it and schedule a time to have the remaining injected.Best,

This i s a great question!  Once a syringe is opened there is a small, but very real, risk of contamination by microdes-bacterial, virus or fungi.  Several studies have shown that the filler is free of bugs after various amounts of time.  There is no consensus, though, basically the amount of time before it is considered unusable is whatever the injector is comfortable with. There are no hard and fast answers about when, exactly, the risk of contamination goes up.  Logically the longer the filler sits after being opened the higher the risk.  In my office we have a hard and firm cut off after 6 weeks.  We record the opening date and throw it away after 6 weeks.  Some studies say that may be to soon but I am uncomfortable letting it sit around any longer.  
So, the long and short of it---it varies with each individual injector.  I'd double check with your injector.
Best of luck to you,
Dr. Amy

According to the
manufacturer of the product, unused portions of filler, after a particular
treatment session, cannot be saved for future use. Though the risk is quite low,
significant complications could occur by storing a sterile product which has
been rendered unsterile during the first treatment. Certainly, some doctors and
some patients are willing to take this risk. But they do so at their own risk,
especially for the doctor. I am unaware of any published medical studies which
have shown us a "safe" timeframe to keep the remaining portion of an
opened syringe of filler, after a treatment session.