How Many Botox Units Are Needed for Upper Lip Plumping?

I agree with most of the others here. Please be cautious of getting Botox into your lips. While some have reported fair results in getting rid of vertical lip lines, there is a significant risk of lip weakness (which is much more unattractive than the lines).
Botox is a great medication when used correctly - but there are likely better choices for lip augmentation.

Botox can be used on the upper lip as a non-approved use for the vertical lines. Botox doesn’t plump the lip. You would need a filler for that. Botox can be used to affect the muscle of the skin-colored upper lip (moustache area, not pink lip) to minimize a “gummy” smile. There are some other unusual techniques as well, but I’m not aware of plumping the lip with Botox.