A non-opioid painkiller and fever reducer
Paracetamol
The everyday first-choice painkiller for mild-to-moderate pain and fever — effective, well tolerated, and safe at the correct amount, but harmful in overdose.
What is Paracetamol?
Paracetamol relieves mild-to-moderate pain and brings down a fever. It is usually the first painkiller to try because it is gentle on the stomach and suits most people, including many who cannot take anti-inflammatories. It is very safe at the recommended amount, but taking too much — even a little too much, repeatedly — can seriously damage the liver, so never exceed the stated dose or double up with other products that also contain it.
Education and reference only. This is a plain-language guide to Paracetamol — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Paracetamol (acetaminophen) is the most widely used medicine in the UK, taken for everyday aches and pains — headache, toothache, period pain, muscle and joint pain — and to bring down a high temperature. It is often the first painkiller recommended because it works well for many kinds of pain, is gentle on the stomach, and can be used by people who cannot take anti-inflammatory painkillers, including many with stomach, kidney or heart problems, and in pregnancy. It is available without prescription and in many combination products.
How it works
Paracetamol is thought to work mainly in the brain and spinal cord, reducing the production and action of chemical messengers (prostaglandins) involved in pain and in setting the body’s temperature. Unlike anti-inflammatory painkillers, it has little effect on inflammation in the body’s tissues, which is why it is gentler on the stomach and kidneys — but also why it may be less effective for pain driven by inflammation.
What it treats
Conditions Paracetamol is used for
Practical use
How to take Paracetamol
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Follow the dose on the label exactly and never take more than the stated maximum in 24 hours, even if the pain has not settled.
- Check other medicines first — many cold-and-flu products and combination painkillers (e.g. co-codamol) already contain paracetamol; do not double up.
- It can be taken with or without food, and alongside an anti-inflammatory painkiller if advised, as they work differently.
- Seek urgent medical help immediately after any suspected overdose, even if you feel completely well — early treatment prevents liver damage.
- Use the weight- and age-based children’s formulations for children, measured with the syringe or spoon provided.
Weighing it up
Advantages & disadvantages of Paracetamol
Advantages
- Effective for many everyday pains and for fever, and pleasant to take.
- Gentle on the stomach and kidneys, and suitable for many people who cannot take anti-inflammatories, including in pregnancy.
- Inexpensive, widely available, and available in tablet, liquid, soluble and suppository forms.
Disadvantages
- Dangerous in overdose — a narrow gap between the maximum safe amount and a harmful one, with serious liver risk.
- Easy to take too much accidentally through combination products.
- Less effective than anti-inflammatories for inflammatory pain.
Practical use
Good to know
The single most important thing with paracetamol is not to take too much. Overdose — even modest amounts above the limit, taken repeatedly — can cause serious, sometimes fatal, liver damage, and the danger is that this can happen with few early warning symptoms. The commonest way people take too much by accident is doubling up: many cold-and-flu remedies, and combination painkillers such as co-codamol, already contain paracetamol, so always check labels and never combine products that both contain it. Take the lowest amount that controls your symptoms, spaced as directed, and keep it out of reach of children.
Who should not take it / use with caution
- People with significant liver disease, or who drink alcohol heavily, should take it only with medical advice and often at a reduced amount.
- Very underweight adults and children need weight-appropriate amounts, as the safe limit is lower.
- Anyone already taking another product that contains paracetamol should not add more.
Monitoring
- None routinely at correct use
- Liver blood tests only after overdose or in significant liver disease
- INR if taken regularly alongside warfarin
Side effects
- At the correct amount, side effects are very uncommon — it is generally very well tolerated.
- Rarely, allergic reactions or skin rashes; very rarely, blood disorders.
- The main danger is not a side effect but overdose, which can silently damage the liver — treat any overdose as an emergency.
Key interactions
- It has few significant interactions at normal use, which is part of why it is so widely recommended.
- Long-term regular use can slightly increase the effect of warfarin (raising the INR) — occasional use is fine, but tell your anticoagulant clinic if you start taking it regularly.
- The risk of liver harm in overdose is higher with heavy alcohol use and with certain enzyme-inducing medicines.
Available as: Tablets, caplets, soluble (dissolvable) tablets, capsules, oral liquids (including children’s Calpol), and suppositories.
Answers
Paracetamol: frequently asked questions
How much paracetamol is too much?
Even a relatively small amount above the recommended maximum, especially taken repeatedly, can damage the liver — so always stick to the dose on the label and never exceed the 24-hour maximum. The commonest accidental overdose is from taking two products that both contain paracetamol, so always check labels.
Can I take paracetamol and ibuprofen together?
Yes — they work in different ways, so they can be taken together or alternated for stronger pain relief if needed, as long as you stay within the correct dose of each. Paracetamol suits many people who cannot take ibuprofen. If you are unsure, ask your pharmacist.
Is paracetamol safe in pregnancy?
Paracetamol is generally considered the preferred painkiller in pregnancy, used at the lowest effective amount for the shortest time. As with any medicine in pregnancy, use it only when needed and check with your midwife, pharmacist or doctor if you have concerns.
What should I do if I have taken too much?
Seek medical help straight away — go to A&E or call 111 — even if you feel completely fine. Paracetamol overdose often causes no early symptoms, but treatment given early is highly effective at preventing serious liver damage, whereas waiting for symptoms can be too late.
Why doesn’t paracetamol help my swollen joint much?
Paracetamol has little effect on inflammation, so for pain driven by swelling and inflammation an anti-inflammatory (like ibuprofen) may work better — though it is harder on the stomach. Your pharmacist can help you choose, or suggest using both.
Authoritative sources
- BNF: Paracetamol.
- electronic Medicines Compendium (SmPC): Paracetamol.
- NICE CKS: Analgesia – mild-to-moderate pain.
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