The cause of rumination syndrome is unknown. However, studies have drawn a correlation between hypothesized causes and the history of patients with the disorder. In infants and the cognitively impaired, the disease has normally been attributed to over-stimulation and under-stimulation from parents and caregivers, causing the individual to seek self-gratification and self-stimulus due to the lack or abundance of external stimuli. The disorder has also commonly been attributed to a bout of illness, a period of stress in the individual's recent past, and to changes in medication.
In adults and adolescents, hypothesized causes generally fall into one of either category: habit-induced, and trauma-induced. Habit-induced individuals generally have a past history of bulimia nervosa or of intentional regurgitation (magicians and professional regurgitators, for example), which though initially self-induced, forms a subconscious habit that can continue to manifest itself outside the control of the affected individual. Trauma-induced individuals describe an emotional or physical injury (such as recent surgery, psychological distress, concussions, deaths in the family, etc.), which preceded the onset of rumination, often by several months.