photostable cosmetic compositions comprising sunscreens , more particularly to cosmetic compositions comprising dibenzoylmethane sunscreens are provided . it is known that dibenzoylmethane and its derivatives are relatively sensitive to ultraviolet radiation and they decompose rapidly under the effect of sunlight . this decomposition is accelerated in the presence of uv - b sunscreens , especially p - methoxycinnamic acid and its derivatives . the present inventors have surprisingly found that cosmetic compositions comprising dibenzoylmethane or its derivative and p - methoxycinnamic acid or its derivative , can be stabilized by incorporating a combination of fatty alcohol ethoxylates and polyalkyleneglycol .