Get emergency medical help if you have signs of an allergic reaction to acetaminophen: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
In rare cases, acetaminophen may cause a severe skin reaction that can be fatal. This could occur even if you have taken this medicine 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. If you have this type of reaction, you should never again take any medicine that contains acetaminophen.
Stop taking acetaminophen and call your doctor at once if you have:
nausea, upper stomach pain, itching, loss of appetite;
excessive sweating and severe tiredness;
dark urine, clay-colored stools; or
jaundice (yellowing of the skin or eyes).
The most common side effects of acetaminophen include:
nausea and vomiting;
headache; or
insomnia
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.
 Acetaminophen side effects (more detail)
