Mineral oil is the most commonly used lubricant laxative in the treatment of encopresis. It is usually given in large quantities (multiple teaspoons) during initial cleanouts to remove very dry, hard stool that is stuck in the colon and cannot be pushed out. This condition is known as an impacted bowel or fecal impaction. Mineral oil facilitates bowel movements by coating the large intestine and the stool with a waterproof film which keeps the stool soft and able to move more easily. Seepage of mineral oil sometimes occurs when mineral oil is used for cleanouts because of the higher than usual doses often required for cleanouts.
During cleanouts mineral oil is often combined with a water retention laxative such as Miralax or Restoralax. However, once the cleanout is finished the mineral is usually discontinued or the dose is significantly reduced so as to avoid seepage or "accidents" during the maintenance phase of treatment when we are relying on the water retention laxative to keep your child's stool softer than normal, e.g. pudding or applesauce consistency.
Contrary to common thought, mineral oil does not cause a vitamin deficiency.