Paracetamol: How Much Is Safe in a Day?

Paracetamol is one of the medicines people ask for most at the pharmacy, for fever and mild pain. Because it is so easy to buy, many assume any amount is fine. It is not. Paracetamol has a daily limit, and going past it can damage the liver.

The adult dose

For 500 mg tablets, the NHS (the UK health service) says one dose is 1 or 2 tablets, with at least 4 hours between doses. In 24 hours you should not take more than 8 tablets, which is 4 grams.

Taking more will not bring a fever down faster. If the right dose has not helped, ask a pharmacist or doctor instead of adding more yourself.

For children, the dose depends on weight and age, and the strength of children's syrup differs from one product to another. Use the measuring spoon or syringe that comes in the box, not a kitchen spoon.

Paracetamol you may not notice

This is the part people miss most often. Many combination cold, cough and headache medicines also contain paracetamol. The U.S. Food and Drug Administration (FDA) counts more than 600 prescription and over the counter medicines that contain it. In the United States it is called acetaminophen.

It often happens like this: someone takes a paracetamol tablet for a fever in the afternoon, then a combination cold medicine at night to sleep. Without realising it, they have taken paracetamol twice.

A study across 22 hospitals in the United States, published in Hepatology, found that paracetamol caused 42% of the cases of acute liver failure it followed. Almost half of those were unintentional overdoses, and 38% of the unintentional group had taken two or more paracetamol products at the same time.

So before taking any medicine, read the ingredients. If it says paracetamol or acetaminophen, count it towards your daily limit.

When to see a doctor

Liver damage from paracetamol often cannot be felt at first. The FDA warns that some people have no symptoms after taking too much. If you or someone at home has taken more than the limit, go to the emergency department or call a doctor straight away, even if they feel well.

Ask a doctor or pharmacist before taking paracetamol if you have liver disease, drink alcohol often, or take other medicines long term.

Before you take paracetamol

• Check the strength of each tablet on the box, since some are 500 mg and some are larger.
• Leave at least 4 hours between doses.
• For adults, no more than 4 grams in a day.
• Check whether any other medicine you are taking also contains paracetamol.

If you are unsure about a dose, the Coapotek pharmacists are happy to work it out with you.

Sources

1. NHS. How and when to take paracetamol for adults.
2. U.S. Food and Drug Administration. Don't Overuse Acetaminophen.
3. Larson AM, et al. Acetaminophen induced acute liver failure: results of a United States multicenter, prospective study. Hepatology, 2005, volume 42, issue 6, pages 1364 to 1372.