It is not uncommon for the nose to be itchy following rhinoplasty. The nasal cast can be irritating and does not allow much oxygen to flow to the outer nasal skin. Itching can also be a sign of healing as the nerves are regenerating. In general, side effects from a rhinoplasty include but are not limited to the following:
1) Congestion
2) Itchy/Irritated nasal skin
3) Swelling
4) Minor pain
5) Numbness
It is important to resist the urge to touch and scratch your nose. Since you are six days post-op, the cast should be coming off in another day or so and you will feel some relief. I would recommend discussing any concerns with your surgeon, as he/she knows the extent of your procedure. Thanks and good luck with your recovery!