Itchy nose can be caused by seafood, pollen or dust mite allergies or other allergens, but it can also be caused by acute upper respiratory tract infection causing congestion of the nasal mucosa resulting in increased secretions that irritate the receptors in the nasal cavity. In the case of allergic rhinitis, you should avoid exposure to allergens such as dust mites, pollen, etc. If you are allergic to seafood, you need to avoid eating seafood. If the nasal itch is caused by increased secretions alone, it is safe to ingest seafood etc.