Found this:
Cradle cap can occur in any baby, and most commonly begins sometime in the first 3 months.
It is not common after the first year of life until the teen years when hormone levels rise and exuberant growth returns. Teens often have a similar scalp condition, but for them we call it seborrhea (though I think “cradle cap” when I see it, remembering how far they have come).
What are the symptoms?
Your adorable baby develops patchy scales and redness on the scalp, even though the early baby pictures showed beautiful baby skin. The scales may appear cracked, greasy, or even weeping.
The same rash is often prominent around the ear or the eyebrows. It may appear in other locations as well, where it is called seborrheic dermatitis rather than cradle cap.
Is it contagious?
No
How long does it last?
In most children, cradle cap is gone by 8 to 12 months and often long before that.
How is it diagnosed?
Cradle cap is diagnosed by physical examination. If it has not improved with simple treatment, other diagnoses should be considered and other tests may be necessary.
How is it treated?
Generally, cradle cap does not need to be treated as long as it doesn’t bother you or the baby. Sometimes it itches.
The gentlest treatment is to simply rub a small amount of baby oil or olive oil onto your baby's scalp. Wait several minutes for the oil to soften and loosen the scales, and brush them away with a soft brush or a dry terry-cloth washcloth.
If the cradle cap is especially pronounced, or if your baby is over six months old, you could also wash the hair with a seborrhea shampoo, such as those containing selenium, salicylic acid, or tar. These shampoos don’t have the "no tears" factor, so be careful or your child may not like bath time as much as they usually do.
If the cradle cap is especially reddened or inflamed, a small amount of over-the-counter cortisone cream may help.
These measures may be needed, off and on, until your baby outgrows the condition. Nevertheless, if the cradle cap does not respond rapidly to these treatments, be sure to inform your pediatrician.