Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Opioid medicine can slow or stop your breathing, and death may occur. A person caring for you should give naloxone and/or seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.
In rare cases, acetaminophen may cause a severe skin reaction that can be fatal. This could occur even if you have taken acetaminophen in the past and had no reaction. Stop taking this medicine and call your doctor right away if you have skin redness or a rash that spreads and causes blistering and peeling.
Call your doctor at once if you have:
noisy breathing, sighing, shallow breathing, breathing that stops;
a light-headed feeling, like you might pass out;
confusion, severe drowsiness;
liver problems--nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
high levels of serotonin in the body--agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, diarrhea.
Serious breathing problems may be more likely in older adults and in those who are debilitated or have wasting syndrome or chronic breathing disorders.
Common side effects include:
drowsiness, dizziness, feeling tired;
nausea, vomiting, stomach pain;
constipation; or
headache.
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.
 Tylenol with Codeine #3 side effects (more detail)
