An itchy nose may indicate allergies, most notably to animals, including cats, dogs, birds, seasonal allergies like hay fever, food, or the start of the common cold. It may also be the result of dry skin.
In allergies, the immune system mistakenly attacks normally harmless substances by releasing histamine and other chemicals into the bloodstream. Antihistamine medications counteract the effects, but they may also cause drowsiness, headache, dry mouth, upset stomach and loss of appetite. Excessive itching is also caused by serious underlying medical conditions, such as basal cell and squamous cell carcinomas, liver or renal failure, herpes zoster infection, or psoriasis.