Codeine can cause mild side effects, if you begin experiencing any severe side effects, consult a physician. Common Codeine side effects include trouble urinating, euphoria, drowsiness, constipation, stomach cramping, dry mouth and feeling light headed. Other Codeine side effects include itchiness, disorientation, vomiting and nausea. The nausea that is experienced with Codeine is usually not as severe as that with Morphine or other opiates.

If you experience severe nausea try lying down for a few minutes and then standing up and seeing if the nausea has subsided. Codeine may not be for everyone, so if you continually experience side effects, or feel ill after taking Codeine, cease taking the medication or consult a doctor.