How soon after my first set of lip injections can I get another round?

This plan is fine. I usually recommend being very conservative with lip injections as you want to look natural and your lips need to fit the rest of your features. 1 syringe (1 mL) is usually adequate for most. However, at two weeks, if you desire more filler you can have additional Juvederm injected without any additional risk. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

Hi there!
Thank you for your question. I would always recommend the less is more approach when it comes to filler treatments. It is best to get a small amount of filler to begin with and then you can always add more to achieve your desired results. I would recommend waiting 2 weeks before reviewing the need for more treatment.
Best Wishes,
Dr. Rupert

In order to achieve natural fuller lips it’s actually not a bad approach to do it in stages 2-3 weeks apart. I usually recommend starting with 1cc wait a couple of weeks and then if needed place another 0.5 -1cc . The reason this works quite well is that sometimes if you try to put too much filler in one sitting because of the immediate swelling caused  and the restistence of the natural structures within the lips the pressure caused by injecting the filler can result in the filler tracking along the earliest path and ending up in unwanted places, leading to lumpiness or the dreaded ‘trout pout’ appearance. 

1 syringe can improve the appearance of your lips, so it's best to do the 1 then assess your results at two weeks. If you still want more, you can always get another syringe. It's easier to do it this way than do too much at once.

Lip filler generally takes about 2 weeks for the product to settle and the swelling to subside.   If at 2 weeks you wish to have another syringe injected i would consult with your injector to see if it is recommended . 

I would recommend waiting about 2 weeks after your first treatment before considering additional filler. The following may be present after your first round of injections:1) Swelling 2) BruisingWaiting for 2 weeks will allow any residual swelling to subside, and give you a better idea of the final result of the treatment. I hope this information helps, and I wish you the best of luck.