Best thing for bad diaper rash La Petite Crème is a highly regarded product for treating diaper rash, especially for babies with sensitive skin. It is known for its gentle yet effective formula that provides relief from irritation, redness, and discomfort caused by diaper rashes. In case the rash doesn't improve or worsens despite using the cream, it's best to consult a pediatrician to rule out infections or other skin conditions.