My 2 month old has a bad cradle cap. which anti dandruff shampoo is best to get? which active ingredient?? ..there are many different ones..

Most will do well: Much of cradle cap is due to retained skin flakes that are not susceptible to the mild ingredients in "tear free" baby shampoos. Active washing with most dandruff shampoos will often do the trick, as well as avoiding baby oil on the scalp or other treatments.A soft cuticle brush to help scrub in the shampoo helps, but keep it away from the eyes.

Selenium Sulfide: Selenium sulfide (Selsun and Exelderm) are often used, but instead a prescription of an antifungal soap such as ketoconazole (2%) shampoo, which can work in a single treatment and shows significantly less irritation than over-the-counter shampoos such as selenium sulfide shampoos, but no adequate and controlled study has been conducted for pediatric use as of 2010 that I am aware of.