Acetaminophen injection is used to treat pain in adults and children at least 2 years old. For moderate to severe pain, acetaminophen is sometimes given with opioid pain medicine.

Acetaminophen injection may also be used for purposes not listed in this medication guide.

Call your doctor at once if you have nausea, vomiting, upper stomach pain, and yellowing of your skin or eyes.

In rare cases, acetaminophen may cause a severe skin reaction that can be fatal. Call your doctor right away if you have skin redness or a rash that spreads and causes blistering and peeling.

Acetaminophen is injected into a vein by a healthcare provider, usually once every 4 to 6 hours.

Doses are based on weight in people who weigh under 110 pounds (50 kilograms). If you use this medicine long term, your dose may change if you gain or lose weight.

You should not be treated with acetaminophen if you are allergic to it or if you have severe liver disease.

Tell your doctor if you have ever had:

• bleeding problems;

• liver disease, cirrhosis, alcoholism, or more than 3 alcoholic beverages per day;

• kidney disease; or

• if you've recently been sick with vomiting or diarrhea;

• if you are malnourished.

Tell your doctor if you are pregnant or breastfeeding.

Pregnancy may be less likely to occur while the mother or the father is using acetaminophen.

In a medical setting you are not likely to miss a dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose can be fatal.

Overdose symptoms include vomiting, stomach pain, and yellowing of your skin or eyes.

Avoid using other medicines that may contain acetaminophen (sometimes abbreviated as APAP).

Drinking alcohol may increase your risk of liver damage.

Get emergency medical help if you have signs of an allergic reaction: 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, even if you took acetaminophen in the past and had no reaction. Tell your caregivers or call your doctor if you have skin redness or a rash that spreads and causes blistering and peeling.

Acetaminophen may cause serious side effects. Stop using acetaminophen and call your doctor at once if you have:

• fever, cough, chest pain, trouble breathing; or

• liver problems--nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of acetaminophen may include:

• cough, breathing problems;

• nausea, vomiting;

• constipation;

• agitation;

• itching;

• headache; or

• sleep problems (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.

Tell your doctor if you also use a blood thinner (warfarin, Coumadin, Jantoven)

Other drugs may affect acetaminophen, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.