Paracetamol

Key facts

• Paracetamol, also called acetaminophen, is a pain reliever and fever reducer used for headache, muscle aches, colds and flu, and mild to moderate pain of many kinds.
• It is taken by mouth every 4 to 6 hours as needed, and effects usually begin within 30 to 60 minutes.
• Taking more than the maximum dose can cause severe, sometimes fatal liver damage, and it is a leading cause of acute liver failure worldwide. Never take two paracetamol-containing products together; it is hidden in many combination cold, flu and pain remedies.
• Seek urgent medical care immediately after any suspected overdose, even if you feel completely well, because early treatment prevents lasting liver damage.

What paracetamol treats

Paracetamol is used for headache, fever, muscle and joint aches, period pain, toothache, and the aches that come with colds and flu. It is often combined with an NSAID or an opioid for stronger pain relief after surgery or injury. Unlike NSAIDs such as ibuprofen, it has little anti-inflammatory effect and does not irritate the stomach lining, so it is often preferred for people who cannot take NSAIDs.

How paracetamol works

Scientists do not fully understand how paracetamol relieves pain and lowers fever. It appears to act mainly in the brain and spinal cord, reducing production of prostaglandins, chemicals that sensitize nerves to pain and drive the fever response in the brain's temperature-control center. It has little effect on prostaglandins elsewhere in the body, so it does not reduce inflammation the way NSAIDs do.

Before you take it

• Never exceed the maximum dose on the label. For most healthy adults this is up to 4 grams (8 tablets of 500 mg) in 24 hours; people with liver disease or heavy alcohol use need a lower limit.
• Check the label of every other medicine you take, especially cold, flu and combination pain products; many contain paracetamol, and doubling up is a common cause of accidental overdose.
• Tell your prescriber about liver or kidney disease, malnutrition, dehydration, or regular heavy alcohol use, since these raise the risk of liver damage even at doses close to normal.

Side effects

At recommended doses, side effects are uncommon: occasional rash or swelling, and rarely blood disorders. In overdose, symptoms can be silent for a day or more before signs of liver damage appear, by which time damage may already be serious.

Seek urgent medical care for:

• Any suspected overdose, even without symptoms.
• Yellowing of the skin or eyes, dark urine, or pain in the upper right abdomen.
• Confusion or unusual bruising.
• Swelling of the face or tongue, or difficulty breathing.

Safety essentials

• Exceeding the recommended dose can cause severe, sometimes fatal liver damage. Never take more than the labeled maximum, and never combine two products that both contain paracetamol.
• Any suspected overdose needs immediate medical assessment, even if you feel fine, since an effective antidote works best when given early.
• Chronic heavy alcohol use, liver disease, or malnutrition can make normal doses risky; ask a pharmacist about a safe maximum if any of these apply to you.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.