I had Juvederm lip injection yesterday and my lips look very fake. Will it get better in time?

Swelling is normal for approximately two weeks, and most significant for the first three days, after lip injections. Juvederm, a hyaluronic acid filler, is hydrophilic which means the gel has an affinity to retain water and cause swelling. Given that you liked the size of your lips directly after the injections, this is likely how it should look after the swelling subsides. Do not judge the size of your lips for two weeks, at which point you may follow up with your injector to dissolve it if you wish. In the meantime, lip swelling can be minimized by sleeping with your head slightly elevated, avoiding things that make you puffy (salty foods, alcohol), a daily long-acting anti-histamine (Claritin), and icing for 10 minutes every hour. Keep in mind that swelling will be the worst when you first wake up in the morning and improve as you are upright throughout the day. For severe swelling, you should immediately follow up with you injector for a cortisone shot to decrease swelling within 24 hours.

You may have had too much put in,You should start out with 1cc of filler and go from there. You do not want to overdo too much filler in the lips. It also depends on the look you are going for.You can always add more filler to the lips if needed. Just remember if you are going to do your lips and you do not want to bruise you should not take any aspirins or anything that will thin the blood since brusing can occur.

The day after Juvederm, most people will have a lot of water retention in the injection areas, so it's not the right time to judge.  It needs 7-10 days.  If it looked pretty good right after injection, then you can expect to go back to that once swelling is done.