Is there a way to prevent the nose from stretching wide when smiling?

Hello ! A great deal of what you see depends on your anatomy around your nose AND your expectations. You have received some good options. If you use a neurotoxin it may work but can impact other features of your smile you like. If you have surgery, you may look better while smiling but may not like what you you look like when you are not smiling. One's smile is dynamic and surgery provides a static change. It is best that you seek a face to face consultation so that your board certified doctor can explain this in greater detail. 

Excision of the alar base can narrow the nasal tip.  Also, alar cinching sutures can further reduce this width.  These procedures are often combined with a formal rhinoplasty procedure. 

Thank you for your question. It would be helpful to review pictures of what bothers you. The open Rhinoplasty procedure can provide access to the underlying structure of your nose for a very predictable approach to reshaping your nose. I suggest that you move forward and consult with a board certified facial plastic surgeon.Best wishes,

alarplasty can help.  The nose still widens when you smile but less.  I tend to avoid external incisions with alar base reduction and use a sill incision that is mostly hidden inside the nose with only mild noticeablity when looking at the face.  It's will improve things quite a bit but remember the nose still widens some even after surgery 

A full set of photographs at rest and smiling are required to make a determination about what can be accomplished with a rhinoplasty procedure.  Wide nostrils can be reduced within an alar-plasty at rest. At the time  of the rhinoplasty procedure, releasing of the smile muscles to the base attachment of the nose can improve the amount widening thst occurs with  smiling, but it's only improvement, not a prevention.