What You Need to Know About Acetaminophen
Edited by Claire Butler
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Acetaminophen is one of the most common drug ingredients in Canada. It can be found in more than 600 different prescription and over-the-counter (OTC) medications under a range of different brand names. The word “acetaminophen” may sound unfamiliar to you, but you probably know many common brand name medicines that contain it, such as Tylenol®. Keep reading to learn more about how acetaminophen can be used safely and effectively in adults.
What is acetaminophen?
Acetaminophen is an analgesic (pain reliever) and an antipyretic (fever reducer). It is used to manage symptoms of fever and pain from headaches, cold & flu, muscle aches, menstrual cramps, arthritis, back pain, toothaches, and vaccination reactions.
Fun fact: acetaminophen is called paracetamol in some countries.
What over-the-counter products contain acetaminophen?
Acetaminophen may come alone or in combination with other medicinal ingredients. Here are some common OTC products that contain acetaminophen:
Several store-brand cough and cold, muscle relaxant, and pain-relieving medications
Always read the “Active/Medicinal Ingredients” section of the label or speak with your pharmacist to be sure. See an example of a product label below!

Who should not use acetaminophen?
Acetaminophen is a generally safe medication, but there are certain situations where a person should not be taking it. Individuals with severe liver disease or chronic alcohol use, and those who are malnourished or are taking certain medications that affect the liver are at an increased risk of serious side effects and should avoid acetaminophen-containing products. Additionally, it is possible to be allergic to acetaminophen, in which case these products should also be avoided.
What are some side effects of acetaminophen?
Acetaminophen is typically well-tolerated and has limited side effects when taken at recommended doses for short-term use. Some possible common side effects include:
Upset stomach
Nausea and/or vomiting
Constipation
Headache
Know your dose
For adults and children aged 12 years and older, the total amount of acetaminophen from all sources should not exceed 4,000 mg a day. This is equal to 8 extra strength (500 mg) tablets or 12 regular strength (325 mg) tablets of OTC acetaminophen such as Tylenol.
Acetaminophen can be taken every 4-6 hours, and it is important to keep track of the amount you have taken to ensure you do not exceed the maximum daily dose. Taking more than the recommended acetaminophen will not provide better or faster relief. You should only ever take one acetaminophen-containing product at a time and only use these products when needed.
If you have liver disease or drink three or more alcoholic drinks per day, the maximum safe daily dose may be less than what the product label indicates. Speak with your pharmacist or health care provider to find the safest dose for you or a suitable alternative.
What’s the harm?
Acetaminophen is broken down by the liver. If a person consumes too much, it can build up in the liver and become toxic. Acetaminophen overdose is the leading cause of acute liver failure in Canada. Even at the recommended dose, long-term use of acetaminophen can increase the risk of liver diseases.
If you have taken more than the maximum daily dose, call your local poison control center immediately – symptoms of liver damage may not appear for many hours after an overdose.
Always ask your pharmacist if you are uncertain if a product contains acetaminophen or if acetaminophen is right for you.
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References
Acetaminophen. Health Canada. Updated September 15, 2016. Accessed February 25, 2022. https://www.canada.ca/en/health-canada/services/drugs-medical-devices/acetaminophen.html
Acetaminophen Product Monograph. In: Compendium of Pharmaceuticals and Specialties. Canadian Pharmacist Association. Updated November 1, 2016. Accessed February 25, 2022. https://www.e-therapeutics.ca
Acetaminophen. In: Lexi-Drugs. Lexicomp. Updated February 24, 2022. Accessed February 25, 2022. http://online.lexi.com