It is usually normal. A healing wound itches; sometimes there can also be a mild allergic reaction to the stitches, to an applied cream or to the plastic retainer. This is not a problem, but please send a photo so that we can give you the right advice.
Natural itching that decreases as healing progresses; a mild allergy caused by the stitches, a cream or the plastic device. The red, raised tissue around the stitches is also usually normal healing tissue.
After looking at your photo (how to take one?), we will recommend whichever of the following is suitable:
Do not scratch, and do not pull at the stitches. Do not change how you use your retainer on your own; this advice is given based on your photo (nostril retainer).
The itching decreases as healing progresses. Healing of the wounds and crusts inside the nose takes 1–1.5 months.
If the redness is spreading, the discharge is increasing, or the swelling and pain are getting worse (when should I message right away?).