Dynamic flaring of the nostrils is caused by contraction of alar portion of the nasalis muscle. Botox functions by relaxing muscles and preventing their contraction. A skilled surgeon who understands the detailed anatomy of the nasal musculature may inject a small amount of Botox into the alar portion of the nasalis muscle to prevent excessive flaring of the nostrils. Please keep in mind, that a Botox injection would only improve the dynamic action of nostril flaring. It is important to keep in mind that relaxing this muscle can affect your ability to breathe through the nose. I recommend that you see a board-certified facial plastic surgeon who commonly performs rhinoplasty and understands the intricate anatomy of the nose. Best of luck!
meanderson, the only thing your can do is see a facial plastic specialist and get an exam. Perhaps Botox will help since this is more of mimetic problem. Good luck!!