Although oxycodone is a useful pain reliever, using it can have a number of negative effects, such as drowsiness, nausea, constipation, and dizziness. Severe cases may result in respiratory depression, a potentially fatal slowing down of breathing, particularly if the medication is taken in large quantities or in combination with other depressants such as alcohol. Because of this, before writing an oxycodone prescription in the United States, doctors must provide patients thorough warnings about these risks.