Acetaminophen (Intravenous)

Acetaminophen belongs to the group of drugs called analgesics (pain relievers) and it is also identified as an antipyretic (fever reducing medicine).


Intravenous (or IV) administered Acetaminophen is only available to patients when prescribed by a doctor and it is not usually self-administered in this form. The usual practice is for a nurse or other medical professional to oversee the injection of this medicine through a needle into a vein over a period of 15 minutes. A patient requiring this medicine may in some circumstances be given instructions and detailed training on the use of an IV system at home - See also dosage below.

Intravenous Acetaminophen injections are usually used in combination with other forms of medication (such as narcotic pain relievers) to relieve pain that is moderate to severe.

Acetaminophen can also be used to reduce a fever, and for mild to moderate pain in some patients, such as backache, headache, menstrual periods, toothaches, cold and flu and osteoarthritis.

Conditions Treated

  • Headache
  • Backache
  • Toothache
  • Muscle aches
  • Cold/flu symptoms
  • Arthritis
  • Fever

Type of Medicine

  • Pain killer (analgesic) /fever reducer (antipyretic)

Side Effects

A patient receiving IV Acetaminophen would normally experience few side effects, other than the reduction of the pain being treated. For all patients, a physician should be consulted in the following cases:

If the pain gets worse or lasts more than 10 days in adults or five days in children; if the fever being treated gets worse or lasts more than 3 days; if new symptoms occur; or if redness or swelling is present.

For adults between the ages of 18 and 60 who take no other medications, the likely side effects are rare, but may include itchiness, constipation, nausea, vomiting, headache, insomnia and agitation. It may also cause some gastrointestinal effects at high doses.

Some uncommon side effects are pain or tenderness in the stomach, loss of appetite, pale stools, dark urine, unusual tiredness or weakness, or yellow eyes or skin. These side effects may indicate liver damage, and any patient experiencing any of these symptoms should seek the opinion of a doctor immediately.

There are also some very rare side effects, these include:

  • Bloody or black stools
  • Bloody or cloudy urine
  • Fever with or without chills (a fever that did not occur prior to taking the Acetaminophen)
  • Pain in the lower back and/or side
  • Skin rash, hives or itching
  • Tiny red spots on the skin
  • Sore throat (not present prior to taking the Acetaminophen)
  • Sores, ulcers or white spots in the mouth or on the lips
  • Sudden decrease in the volume of urine
  • Unusual bleeding or bruising

If a patient experiences any of these very rare side effects, the patient should seek the advice of a physician immediately.

With an intravenous injection of Acetaminophen, there is a slight risk of Anaphylaxis. Anaphylaxis refers to a serious allergic reaction that would require immediate medical attention. It's important to see a doctor immediately if there is any rash, trouble breathing or swallowing, itching or hoarseness after being given Acetaminophen.

There is also a risk of a serious skin reaction, so in the case of blistering, skin lesions, loose skin, peeling, skin rash or severe acne, ulcers or sores, it's also very important to seek medical attention to ensure that you or your child's condition does not worsen.

Some of the rare side effects may be the result of liver damage. Adults who regularly consume more than three glasses of alcohol per day, or adults who have a pre-existing liver disease, should avoid taking Acetaminophen in any format and consult a physician before taking this drug.


There is not always a dosing schedule connected to the use of IV Acetaminophen as it is generally administered as needed under very close medical supervision.

A patient's dosage level will be set by their doctor based on various factors such as medical history and body weight. So it is extremely important that the patient keeps their Doctor aware of any changes in their weight and general health when taking this medicine. For example, for an individual under 110 pounds (50 Kilograms) lower doses are used.

If self-administering (especially if at home) the patient must be very carefully trained and confirmed as competent in the use of the equipment involved. They must also have a very clear knowledge of how to understand the labelling of the strength of the solution in the single use vials (bottles) provided to them and follow all the instructions given precisely.

An overdose of Acetaminophen can cause liver damage or death. Any indication of an overdose requires immediate emergency medical attention.

it is extremely important to bear in mind at all times that Acetaminophen is added as a component to many other over the counter medications, such as cold remedies, allergy remedies, and night time sleep aids, for example. Therefore, patients need to be made acutely aware that no other Acetaminophen containing products should be used when they are using IV Acetaminophen as this could lead to an inadvertent overdose.

Major Drug Interactions

While some medicines should never be used together at all, there are other cases where two different drugs may be used together even if certain interactions could occur. If a patient is taking one medication that should not be used with Acetaminophen, the patient's physician may decide to prescribe a different dose or form of the medication along with or recommending other precautions.

When prescribed IV Acetaminophen, a patient should inform their doctor in the event that they are taking any of the other medicines listed below, as well as any other over-the-counter medications they might be taking. The drugs below are listed in order of their importance. This list may not include every drug that has some form of interaction with Acetaminophen.

Use of the following medicines is not recommended without the approval of a physician:

  • Imatinib
  • Isoniazid
  • Pixantrone
  • Pneumococcal 13-Valent Vaccine, Diphtheria Conjugate

When using Acetaminophen alongside any of the medicines listed below, there is potential for an increased risk of some of the potential side effects, however it may be useful to use both drugs together. A doctor will advise patients whether such a combination is useful, and should recommend the correct dose as well as how frequently the medications are taken. These medicines include:

  • Acenocoumarol
  • Carbamazepine
  • Fosphenytoin
  • Lixisenatide
  • Phenytoin
  • Warfarin
  • Zidovudine

The use of alcohol (ethanol) with Acetaminophen is not recommended due to the risk of liver disease. Serious side effects include fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash or itching, nausea, vomiting, and yellowing of the skin or of the eyes. For patients who use alcohol products, it is very important that they inform their doctor of the frequency and quantity they are using.


As noted above, one of the biggest risks when taking Acetaminophen comes from the potential to take amounts in excess of the recommended daily dose. Acetaminophen has been associated with cases of severe liver failure, even requiring a liver transplant or resulting in death. These cases of liver damage most often result from the taking more than one product that contains Acetaminophen.

As a result, dosing accuracy is very important with Acetaminophen in order to avoid errors which could result in accidental overdose and death, particularly in children. Severe liver damage may occur if more than the maximum dosage is taken within a 24-hour period. In addition, patients who consume more than three alcoholic drinks per day are also placed at higher risk of liver damage.

Patients should inform their doctor of the following when seeking medical advice regarding the use of Acetaminophen:

  • Other medications being taken, including all over the counter medications
  • Alcohol consumption or abuse - frequency and amount
  • History of severe kidney disease
  • History of liver disease (including hepatitis)
  • Phenylkeutonuria (PKU) - brands of Acetaminophen can include aspartame, making this condition worse

Children are at risk of taking excessive and even toxic doses, due to Acetaminophen being included in many cold or flu medications. It is important to be sure that the total daily dose from all sources does not exceed the recommended amount. Children should not exceed 5 doses within a 24-hour period.


Acetaminophen may be stored in a closed bottle or other container. This medication should be kept at room temperature, and away from moisture, heat, or direct light, based upon the manufacturer's recommendations. Do not freeze this medication. The bottle should be kept closed when not in use, and in a childproof bottle. If the drug is being provided in suppository form, it may be kept in the refrigerator, but do not freeze.

Acetaminophen should always be kept out of the reach of children, due to the risk of toxic overdosing. As with all medications, it is important to dispose properly of any outdated medicine or medicine which is no longer needed. For proper disposal, ask a healthcare professional.


Acetaminophen is a very useful drug for treating a wide variety of aches and pains but its use still requires careful assessments are made by the patient and doctor.

For intravenous route delivery of this drug it is key that consideration be given to areas around the following topics:
Allergies- The patient must advise their doctor if they have ever been known to have an unusual or adverse or general allergic reaction to this or any other medicine. This will usually be information the patient is required to provide through the taking of a detailed medical history.

Age - With regard to paediatric patients the safety and efficacy of using IV Acetaminophen has not been established for children below two years of age. At the other end of the age spectrum no geriatric specific problems or issues are documented that indicate a limit to the usefulness of injected Acetaminophen for elderly patients.

Pregnancy and breastfeeding - A clear connection to adverse maternal outcomes has not been shown in studies looking at IV Acetaminophen use during pregnancy. However, as information and advice emerging from research may change the advice of the patients' doctor will be important before any prescription is provided.

With regard to breastfeeding, caution is recommended as tests have shown that the drug is excreted into breast milk in very small amounts and there has been a report of a maculopapular rash in a 2-month old nursing infant.

More generally concerning this medicine, as noted and stressed throughout the details in this article it is available over the counter in different products. It may be sold as a single active element in a pill, but it is also often found in combination with other over the counter drugs such as cold and allergy medication. As a medication used to relieve muscle aches, headaches, toothaches, backaches and other pain, it is very successful, and has only a few rare side effects. It is the fact that it is widely available which poses a risk of overdose and acute liver damage, particularly for children.

With Acetaminophen available in many over the counter forms, patients should be aware of the potential for liver damage as a result of overdosing. When using this medication, patients should not exceed the recommended daily dose, based on all sources including other combination medications. In addition, young children, patients with a history of liver damage, and patients who consume more than three alcoholic drinks per day are not advised to use Acetaminophen. If recommended doses are exceeded, possible severe liver damage can occur, including liver failure and death. When using Acetaminophen, patients who fall into one of these three high risk categories should consult their physician for recommended daily dosages. Any patient who experiences the symptoms of liver damage, as well as any of the rare side effects, should consult a doctor immediately.