Baby Acne
Acne is very common in newborns. Pimples can show up anytime between 2 weeks and 2 months of age and last until your child is between 4 and 6 months old. As with adult acne, it usually amounts to some small whiteheads on the face, or less frequently on the back. (These pimples are different from the little red bumps called milia that your baby may have had on her face at birth. Milia usually go away within two weeks.) If the baby has a rash anywhere else on her body, or if it's scaly or red and rashy, check with your pediatrician. Your baby could have another condition such as cradle cap or eczema.
Baby acne is caused by the hormones the baby gets in the womb and through breast milk. Since your baby isn't producing these levels of hormones herself, once you're done breastfeeding and they're out of her system, the acne will clear up.
It's probably best to just leave it alone. Topical remedies and vigorous washing could irritate your baby's sensitive skin, and the condition will be a distant memory in a few short weeks or months anyway. Your pediatrician probably won't prescribe any treatment unless the acne looks severe enough to scar.