After Botox for a gummy smile, is it usual to have a numb feeling in the upper lip for the entire 3 months the Botox lasts for?

Numbness is not usually a side effect of Botox. You may be experiencing altered sensation because of the decrease in contraction of the muscle. Schedule a follow up with your injector and be assessed. 

True numbness after Botox injections is not common.  It would be helpful to know if the feeling is the same on both sides of the lip or if it is limited to just one side.  It is important to differentiate true numbness from the awkward, heavy feeling that inability to fully move a muscle can sometimes produce.

Numbness after Botox is not common and i'm unsure why this would have happened.  It is normal to feel a "heaviness" in this area that can persist till the Botox wears off.  Best, Dr. Emer.

Hi Sunset.  A little bit of heaviness or "numbness" is normal after Botox for a gummy smile.  The feeling should not last a full three months and it will get better as the product slowly wears off.  Good luck.

We routinely do this in our practice and other than heaviness that is experienced, patients do not complain of numbness in the lip. 

the overwhelming majority of people treated for gummy smile do not have any symptoms afterward and certainly it would be exceptional it a problem lasted 3 months...often what people complain of in reality is just the change in feeling of muscles that have temporarily been placed at rest and as a result feel some "heaviness"...kind of like after a dental treatment where you feel your tooth or bite is a little off for the first several weeks until your nervous system gets used to the new normal...hope you do well...are the cosmetic results what you anticipated?