Children: Betamethasone belongs to the family of medications known as corticosteroids. Children may be more likely to experience side effects (e.g., slowing down of growth, delayed weight gain), especially if large amounts of this medication are used for long periods of time. The use of this medication by children should be limited to the smallest amount that will be effective for the shortest period of time. Discuss the risks and benefits of the use of this medication by children with your doctor.. Each gram contains betamethasone as betamethasone 17-valerate 0.05% in a water washable aqueous base. Nonmedicinal ingredients: ceteareth-15, cetyl alcohol, chlorocresol, mineral oil, phosphoric acid, polyethylene glycol 1000, propylene glycol, purified water, sodium hydroxide, stearyl alcohol, and white petrolatum.. How to use Betaderm Cream. Use this medication on the skin only. However, do not use it on the face, groin, or underarms unless directed to do so by your doctor..