How long will my newborn’s face rash last?

10-12 weeks. The normal newborn acne or newborn rash can last 2-3 months. If the baby is irritated by it, scratching , itching, etc. Consult your doctor.
2-4 weeks. If the rash lasts longer than this, seems to be getting worse, or appears to be bothering your baby, she should be examined.