Synergistic effect of hormone can be explained as when two or more hormones combine to produce effects greater than the sum of their individual effects. A hormone is said to have a synergistic effect on the action of a second hormone when it enhances the responsiveness of a target organ to the second hormone or when it increases the activity of the second hormone. For example, the ability of mammary glands to produce and secrete milk requires the synergistic action of many hormones such as estrogen, cortisol, prolactin, oxytocin, and others.