Using a small amount of botox in the area of the bunny lines can help relax that muscle and reduce the bunny line wrinkles formed from "scrunching the nose" like in response to when a person smells something bad.
If the botox injections directly in the area of the bunny lines doesn't smooth out enough, then it is possible that the person is scrunching their nose with other muscles on the side of their nose. These muscles can also be injected, but have a higher risk of side effects and will likely causes changes in the way the person smiles, so I don't inject those areas.
In summary, botoxing the bunny line area may show full improvement, but possibly partial improvement depending on the extend of the muscles used to cause them in the first place. This is a similar phenomenon as botox for the crow's feet. The crow's feet wrinkles also look much smoother when the person doesn't move their face and simply squints their eyes without using their cheeks. However, if the person smiles really big, or they squint hard using their cheeks, since they can't squint with their eye muscles, some crow's feet lines can also be seen.
On a side note regarding bunny lines, a patient of mine who is a long time botox user noted that since she has been using botox for the frown lines between her eyebrows, and is unable to frown with these muscles and pull the brow downwards to partially cover her eyes, she has begun doing the opposite and pushing her cheeks upwards harder to compensate for the reduced ability of her brow muscles to work. As a result, she notes that she sees more bunny lines. Since she made this observation, she has asked some of her friends who are fellow users of botox and said that they also noticed the same thing.
I figured that I would add that last point in, just in case you are already a botox user, but started to notice these bunny lines for some odd reason.
Best,
Dr. Yang