Demerol is pain relief medicine.Demerol belongs to a class of drugs known as opioids and this is similar to morphine. This medicine basically works with the brain to change how your body feels and responds to pain. Buy Demerol Online. This medicine should not be taken for long term to cure pain it should be taken for a short period of time. Take this medicine as prescribed by your doctor and you can take this medicine every 3-4 hours. You can take this medicine with or without food. If you have a problem with nausea then you can take this medicine after food.