Demerol 50mg Tablets and Oral Solution are used for the management of acute pain severe enough to require an opioid analgesic. The usual dose of Demerol for adults is 50 to 150 mg every 3 to 4 hours. Tell your doctor if you are pregnant or plan to become pregnant while using Demerol. Demerol passes into breast milk and may harm a nursing baby. Breastfeeding while using Demerol 50mg is not recommended.