lip flip vs filler: which one do you need

What's the difference between lip fillers and lip flip? I see both terms online but can't figure out which is right for me.

Lip flip uses botox (not filler) injected above the upper lip to relax the muscle, so your lip uncurls and appears fuller when you smile. It lasts about 2-3 months and adds no volume. Filler adds actual physical volume. Some people do both for maximum effect.

I've done both separately and together. The lip flip alone gave me a nice shape when I smiled but didn't solve my lack of volume. Filler alone made my lips bigger but my smile still looked tight. Combining them was the winner. For me, the procedure that finally worked was getting a tiny bit of filler plus a lip flip a week later. I found a blog comparing lip augmentation procedure options that explained how the two techniques complement each other. If your natural lip curls inward when you relax, start with a lip flip. If you just want fuller pout, go for filler. Want both? Do filler first, then lip flip two weeks after to adjust the shape.