What can cause skin to itch?

So many things! Among them:

Reaction to laundry soap, dryer sheets or other cleaning products

Reaction to new shampoo, soap or styling products

Dust allergy, particularly in a home not your own

Allergy to pet dander in the air

Dry skin

Seasonal allergies

Nerves or stress (some people break out in hives)

Friction, like if you aren't used to wearing a turtleneck and then you wear one all day.

Allergic reaction to someone else's perfume, particularly the knockoffs of expensive ones

Dry skin will cause it, it can be fixed with a moisturizer. If the humidifier on a furnace isn't working properly it contributes to dry skin too as well as static electricity in carpets and hair etc.

Hair

Dry skin, sweetie. Lol

so many different things and far too many to mention on here but the most common is allergy.