Itchy nipples are a relatively common problem. Women with small breasts may go without a bra and their nipples are irritated by clothing moving across them, or a loose fitting bra may constantly move across the nipple irritating it.
Other causes include synthetic materials in a bra, allergies to soaps, perfumes and washing powders, and fungal infections such as thrush (common in breastfeeding mothers).
Treatments include lanolin and other skin moisturisers, anti-itch creams, antifungal creams if thrush present, or prescribed mild steroid creams. Padding a bra may help small-breasted women, and an adhesive dressing over the nipple can give quick relief.