I have a bottom lip that twitches especially when I am anxious. Can it be helped by Botox?

It depends. Certain muscles, especially around the mouth, cannot be treated with a neurotoxin like Botox because it prevents the muscle from moving. In areas like the forehead or between the brows, this is a desired effect, however, it may not be if the affected muscle is one that helps us smile or frown. Tremors are treated in a number of different ways. Personal evaluation in essential before recommendation

Botox in the lower lip must be performed with very low doses and only in specific locations or the wrong muscles will be affected resulting in drooling or spitting food, as well a asymmetry.  Make sure your physician I very familiar with injection in this area.

It is possible that Botox may be able to help this but it will be difficult to do without side effects. see a board certified neurologist to get an evaluatiojn