Get emergency medical help if you have signs of an allergic reaction to codeine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Like other narcotic medicines, codeine can slow your breathing. Death may occur if breathing becomes too weak.
A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.
Call your doctor at once if you have:
noisy breathing, sighing, shallow breathing, breathing that stops during sleep;
a slow heart rate or weak pulse;
a light-headed feeling, like you might pass out;
confusion, agitation, hallucinations, unusual thoughts or behavior;
feelings of extreme happiness or sadness;
seizure (convulsions);
problems with urination; or
low cortisol levels--nausea, vomiting, loss of appetite, dizziness, worsening tiredness or weakness.
Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.
Serious side effects may be more likely in older adults and those who are overweight, malnourished, or debilitated.
Long-term use of opioid medication may affect fertility (ability to have children) in men or women. It is not known whether opioid effects on fertility are permanent.
Common codeine side effects include:
feeling dizzy or drowsy;
nausea, vomiting, stomach pain;
constipation;
sweating; or
mild itching or rash.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Codeine side effects (more detail)
