The patient should know how to use Opana ER 20 mg, what is the side effects, etc. Swallow the pill as a whole on an empty stomach at least 1 hour before or 2 hours after eating. Do not stop this medication without consulting the doctor. The patient should give all the information about himself like, his food habit, vitamin medicine taking, any disease before taking the medicine, etc. If the patient will find any serious side effects like, difficulty in breathing, sweating, fever, fast heart rate, loss of appetite, diarrhea, vomiting, dizziness, etc. visit your doctor or physician for a medical check-up.