As is the case for all medications, acetaminophen must be used wisely, by taking certain precautions. Here is some information on the subject.
Acetaminophen: well-known, popular… and underestimated
Who has never taken acetaminophen in their life? Better known by its brand name (Tylenol®), acetaminophen is a commonly used pain reliever in Canada that is also effective against fever. It is found in more than 700 over-the-counter and prescription drug formulations in various strengths and formats (tablets, liquid gels, capsules, syrup, suppositories, etc.).
It is primarily used for relief of pain due to multiple causes:
- sore throat
- back pain
- menstrual pain
- joint pain (e.g., osteoarthritis)
It is also widely used in products formulated to ease cold and flu symptoms, where it is combined with other medications (e.g., cough syrup, decongestant, antihistamine, etc.) in a single formulation.
Despite its popularity and its importance in managing pain and fever, misuse of acetaminophen can carry health risks that can sometimes be serious.
Adherence to dosage
As with any medication, the recommended dosage of acetaminophen should never be exceeded. Dosage recommendations vary according to age.
For adults and children aged 12 years and older, the maximum recommended daily dose is 4000 mg. In practice, this corresponds to:
- 8 extra-strength tablets (500 mg/tablet)
- 12 regular-strength tablets (325 mg/tablet)
A single dose of acetaminophen usually ranges from 325 to 1000 mg. The interval between doses is usually 4 to 6 hours. However, more concentrated formulations are available with an 8-hour duration of action.
In children, the recommended dosage varies according to weight and age. Although dosing instructions appear on the packaging of children's products, it is best to consult a pharmacist. They can calculate the exact dose to give according to your child's situation and weight, and explain how to measure it accurately (in millilitres or tablets, for example).
The safety profile of acetaminophen
If the recommended dosage instructions are followed, acetaminophen is one of the safest drugs available.
However, the potential for toxicity increases in proportion to the dose ingested. For example, an overdose of acetaminophen may cause liver damage. This may occur after ingestion of a single very high dose or multiple doses exceeding recommendations over a period of time. Various factors such as alcoholism or liver disease (i.e., hepatitis) may predispose a person to liver toxicity.
Every year in Canada, there are thousands of cases of self-induced or accidental acetaminophen intoxication. Many of these cases require hospitalization. Those affected may develop liver damage, which can sometimes lead to acute liver failure. In more severe cases, the person may require a liver transplant or even die.
In the event of acetaminophen overdose you should immediately contact a poison control centre.
Acetaminophen can also interact with other drugs. For example, taking a high dose of acetaminophen may increase the anticoagulant activity of warfarin (Coumadin®).
Tips for optimal and safe use
Acetaminophen can be taken without any concern unless there is a particular warning or contraindication. To ensure you get the relief you need without exposing yourself to risks, it is recommended that you:
- Follow the recommended dosage to the letter.
- Never take a dose earlier than indicated.
- Take note of when you took the last dose as well as the amount.
- Never take more than one medication containing acetaminophen at a time.
- Always read over-the-counter packaging carefully. If the product contains acetaminophen, the manufacturer must indicate this on the label. If in doubt, ask the pharmacist for help.
- Whenever possible, avoid taking acetaminophen if you do not have pain or a fever. When taking products with several active ingredients in the same formulation, you may be taking a drug that you do not need.
When taking acetaminophen, you may need to be extra careful because of your health, medical history or other drugs you are taking. Speak to your doctor or pharmacist if you are unsure.
Consult your pharmacist if you have any questions about the optimal and safe use of over-the-counter drugs.