How does this medication work? What will it do for me?
Acetaminophen belongs to a group of medicines called analgesics (pain relievers) and antipyretics (fever reducers). It works quickly to relieve pain caused by conditions such as headache and osteoarthritis, and to reduce fever caused by infection. Unlike acetylsalicylic acid (ASA), which is also an analgesic and antipyretic, acetaminophen does not reduce inflammation.
Acetaminophen is used by itself as well as in combination medication products for cough, cold, and pain relief.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
This medication is available as a 500 mg tablet.
How should I use this medication?
Acetaminophen can be used by all age groups in recommended doses.
Children (general): 10 to 15 mg per kg of body weight, every 4 to 6 hours, to a maximum of 65 mg/kg in 24 hours. Children should not take more than 5 doses in 24 hours unless advised by a doctor. For children under 6 months of age, consult a doctor.
Adults: 325 mg to 650 mg every 4 to 6 hours to a maximum of 4,000 mg in 24 hours.
Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without talking to your doctor. Always take acetaminophen exactly as prescribed by your doctor.
This medication is generally used as needed for pain or fever, except in the case of osteoarthritis and some other chronic conditions, when it is often taken on a regular basis in order to keep pain under control. In these circumstances, if you miss a dose of this medicine and you remember within an hour or so of the missed dose, take it as soon as you remember. However, if you do not remember until it is almost time for the next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
When used for self-medication of pain, acetaminophen should not be used for longer than 10 days by adults or 5 days by children unless advised by a doctor.
Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
This medication is available under multiple brand names and in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Do not take this medication if you:
- are allergic to acetaminophen or any ingredients of the medication
- have liver disease caused by acetaminophen
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- black, tarry stools
- bloody or cloudy urine
- fever with or without chills (not caused by condition being treated and not present before treatment)
- pain in lower back or side (severe or sharp)
- pinpoint red spots on skin
- skin rash, hives, or itching
- sore throat not present before treatment and not caused by the condition being treated
- sores, ulcers, or white spots on lips or in mouth
- sudden decrease in amount of urine
- unusual bleeding or bruising
- unusual tiredness or weakness
Stop taking the medication and seek immediate medical attention if any of the following occur:
- signs of a serious allergic reaction:
- difficulty breathing
- swelling of face or throat
- signs of overdose:
- increased sweating
- nausea or vomiting
- loss of appetite
- stomach cramps or pain
- swelling, pain, or tenderness in the upper abdomen or stomach area
- symptoms of liver damage:
- abdominal pain
- dark urine
- itchy skin
- pale stools
- yellow skin or eyes
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
HEALTH CANADA ADVISORY
September 15, 2016
Health Canada has issued new restrictions concerning the use of acetaminophen. To read the full Health Canada Advisory, visit Health Canada's web site at www.hc-sc.gc.ca.
A previous advisory on acetaminophen was issued on July 9, 2015. To read the full Health Canada Advisory, visit Health Canada's web site at www.hc-sc.gc.ca.
Alcohol: Chronic excessive use of alcohol may increase the risk of liver damage due to acetaminophen, even when acetaminophen is used at normal doses.
Avoiding overdose: Acetaminophen is a frequent cause of accidental poisoning for infants and children. Keep the medication out of the reach of children, use an oral syringe to measure the dose, read the package carefully, and consult your pharmacist or doctor to confirm the best dose for your child. Adults may also be at risk of an acetaminophen overdose, especially if they take multiple products containing acetaminophen. Acetaminophen is a common ingredient in many non-prescription medications for colds and flu, pain, arthritis, and fever. Check the product label on all medications you are taking to make sure you are not exceeding the recommended dose of acetaminophen. An overdose of acetaminophen can lead to potentially fatal liver damage.
Pregnancy: Acetaminophen is reported to be safe for short-term use in pregnancy at recommended doses.
Breast-feeding: Acetaminophen passes into breast milk but is not likely to have a harmful effect on the infant when used at recommended doses.
What other drugs could interact with this medication?
There may be an interaction between acetaminophen and any of the following:
- acetylsalicylic acid (ASA)
- blood thinners (e.g., warfarin)
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.