Baby acne generally lasts longer with breast-fed babies, since the same residual, oil-triggering hormones that the baby was exposed to in the uterus can come through the mother's milk, too. As a result, it often begins clearing up as your baby is weened off of breast-milk. It may even clear up sooner if your baby's oil glands have matured enough to handle the hormones before then.
Acne treatment that you apply to the skin: Most acne treatments are applied to the skin. Your dermatologist may call this topical treatment. There are many topical acne treatments. Some topicals help kill the bacteria. Others work on reducing the oil. The topical medicine may contain a retinoid, prescription-strength benzoyl peroxide, antibiotic, or even salicylic acid. Your dermatologist will determine what you need.