Skilled nurse instructed patient about medication Oxycodone is used to treat moderate to severe pain. Take this medicine exactly as prescribed by your doctor. Never share the medicine with another person. Misuse narcotic pain medication can use addiction overdose, or death, especially in a child or other person using the medicine without a prescription. Common Oxycodone side effects may include: mild drowsiness, headache, dizziness, tired feeling; stomach pain, nausea, vomiting, constipation, loss of appetite, dry mouth, or mild itching.