Paracetamol: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on Nov 13, 2023.

1. How it works

• Paracetamol is what acetaminophen is called in almost every country in the world apart from the U.S., Japan, and Canada (where it is called acetaminophen). Paracetamol is the same as acetaminophen.
• Paracetamol is used to relieve pain. Experts aren't sure exactly how paracetamol works but suspect it may activate descending serotonergic inhibitory pathways in the CNS and other nociceptive pathways (nociceptive pain describes pain from physical or potential damage to the body such as that from a sports injury or dental procedure). Inhibition of the hypothalamic heat-regulating center gives paracetamol its fever-lowering effect.
• Paracetamol belongs to the class of medicines called analgesics (pain relievers); it is specifically a non-narcotic analgesic. It may also be called an antipyretic because it will bring down a fever.

2. Upsides

• Effective for the temporary relief of minor aches, pains, and headaches. May be used in the treatment of many conditions such as arthritis, backache, colds, menstruation pain, and toothache.
• Also, lowers a fever but does not control inflammation.
• First choice for mild-to-moderate pain due to its efficacy, minimal toxicity, and low cost.
• At low dosages, it lacks the gastrointestinal side effects associated with NSAID pain relievers (does not cause ulcerations, bleeding, or perforations).
• May be combined with strong opioids for the treatment of severe pain.
• Available in a range of formulations including liquid, oral tablets, oral disintegrating tablets, chewable tablets, controlled-release tablets, dispersible tablets, injectable, and rectal preparations.
• Generic paracetamol is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Rarely, may cause itchiness, constipation, nausea, vomiting, headache, insomnia, and agitation. May cause gastrointestinal side effects at high dosages.
• The potential for liver damage exists, even at recommended dosages. The risk is increased with higher dosages, a shorter interval between doses, in people who drink three or more alcoholic drinks per day, when taken with other medications that also contain paracetamol or acetaminophen, and in patients with pre-existing liver disease.
• Considered less effective for pain relief than NSAIDs but is associated with a lower risk of side effects.
• Although it may relieve arthritis pain, it does not affect the underlying inflammation and swelling of a joint.
• May not be suitable for some people including people who regularly consume three or more glasses of alcohol per day and those with liver disease.
• There are many brands of paracetamol available and it is commonly used in combination with other ingredients for cold, flu, and pain relief. This may be confusing to some people and result in inadvertent double-ups in dosing.
• May interact with some other medications including warfarin.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

• Paracetamol is another name for acetaminophen which is an effective mild pain reliever with a low risk of side effects.

5. Tips

• May be administered without regard to food; although food may decrease any reported stomach upset.
• Do not exceed the recommended dosage, because this may put you at risk of liver toxicity. Adults and teenagers who weigh at least 110 pounds (50kg) should not take more than 1000mg of paracetamol in one dose or more than 4000mg in 24 hours. Children younger than 12 years should only take the dosage recommended to them on the label (this varies depending on their weight and age).
• Always seek your doctor's advice before administering paracetamol to children aged less than two. If you are giving pediatric paracetamol, always use the dosing syringe provided or another suitable properly calibrated measure. Do NOT use a kitchen teaspoon.
• Shake liquid paracetamol before use. Chewable tablets should be properly chewed before swallowing. Hands should be dry before handling the paracetamol disintegrating tablet, then the tablet should be placed on the tongue and allowed to fully dissolve before swallowing. Paracetamol disintegrating granules should be dissolved in at least four ounces of water; the mixture stirred, and then drunk straight away.
• Men should not drink more than two alcoholic drinks a day and women no more than one alcoholic drink per day while taking paracetamol.
• Contact your doctor if symptoms worsen, if redness or swelling occurs in the painful area, if a fever lasts longer than 3 days (all ages), or for persistent pain (excluding sore throat) of longer than 10 days in adults, 5 days in children and adolescents, or 3 days for infants.
• Contact your doctor immediately if you or your child has a severe sore throat, that persists for longer than 2 days, or is followed by fever, rash, headache, nausea, or vomiting.
• Be careful not to administer other products containing paracetamol or acetaminophen at the same time. Paracetamol is often an ingredient in combination cold and flu remedies.
• Seek urgent medical attention if you develop pain in your upper abdomen, dark urine, loss of appetite, yellowing of the skin or eyes, or clay-colored stools.
• Do not take paracetamol without your doctor's advice if you are pregnant.

6. Response and effectiveness

• The pain-relieving effects of paracetamol occur within 30-60 minutes of administration of the oral tablets. The effects last for three to four hours.

7. Interactions

Medicines that interact with paracetamol may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with paracetamol. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may have a moderate interaction with paracetamol include:

• anticonvulsants, such as fosphenytoin or phenytoin
• barbiturates
• busulfan
• carbamazepine
• dapsone
• flucloxacillin
• isoniazid
• lamotrigine
• phenylephrine
• probenecid
• warfarin.

Alcohol may enhance the liver toxicity of paracetamol.

Note that this list is not all-inclusive and includes only common medications that may interact with paracetamol. You should refer to the prescribing information for paracetamol for a complete list of interactions.

References

• Paracetamol 04/2023. Drugs.com. https://www.drugs.com/paracetamol.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use paracetamol only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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