Dysphoric milk ejection reflex (D-MER) is a condition in which individuals who breastfeed develop negative emotions that begin a few minutes before milk ejection and end while breastfeeding. It is very likely to recur in subsequent breastmilk ejections and may only affect the initial phase of breastfeeding. The dysphoria is caused by the secretion of prolactin and possibly the inhibition of dopamine release during milk ejection.

The prevalence of D-MER is about 9%. D-MER appears to be unrelated to the individual's birth or life experiences. It can occur acutely after several normal lactations.

D-MER always presents as an emotional reaction but may also produce physical symptoms like a churning sensation in the bottom of the stomach. Symptoms may spontaneously resolve by 3 months or may persist throughout breastfeeding. The individual's ability to maintain a proper breastfeeding schedule may be affected by the symptoms, leading to early discontinuation of breastfeeding.