Paracetamol vs ibuprofen: how they differ and when each is used

Both are among the most widely used painkillers in the UK, and both are sold without prescription, but they are not versions of the same drug. Paracetamol has a central action and is a mild to moderate painkiller and fever reducer. Ibuprofen belongs to the NSAID group and has an anti-inflammatory effect in addition to pain relief.

This difference means one may be more suitable for certain kinds of pain and one may be unsuitable for certain people. Understanding why helps people choose more safely and recognise when a pharmacist's advice is needed.

Paracetamol is generally well tolerated at recommended doses and does not irritate the stomach, so it is often the first choice for people who cannot take NSAIDs, including many with ulcers, kidney disease, heart disease or asthma triggered by NSAIDs, and it is commonly used in pregnancy where advised by a clinician. It does little for inflammation.

The central safety issue is dose. The liver processes paracetamol, and exceeding the daily maximum, or taking more than one product that contains it, such as some cold and flu remedies, can cause liver injury. Lower body weight, malnutrition, heavy alcohol use and some liver conditions increase vulnerability, and the pack or a pharmacist will advise on dose adjustments.

Ibuprofen is useful where inflammation contributes to pain, as in muscle and joint injuries, toothache and period pain. It should be taken with or after food, at the lowest effective dose and for the shortest time, as directed on the leaflet. It is not suitable for everyone: people with a history of stomach ulcers or bleeding, kidney disease, heart failure or asthma sensitivity should check first, and it is generally avoided in later pregnancy.

Interactions matter, particularly with blood thinners, some blood pressure and heart medicines, diuretics, lithium and methotrexate. A pharmacist can check your medicines before you buy.

NHS and MHRA advice is consistent: read the label, follow the dose and interval, do not take more than one product containing the same ingredient, and use the lowest effective dose for the shortest time. For paracetamol, there is particular emphasis on not exceeding the maximum daily dose; for ibuprofen, on avoiding it in people with relevant conditions and on taking it with food.

The two are sometimes used together or alternately for stronger pain on professional advice, since they work differently, but this should be guided by a pharmacist, doctor or the product label, especially for children, older adults or anyone with other conditions. Pain that is severe, getting worse or lasting beyond a few days needs medical assessment rather than escalating self-treatment.

• Headache, fever or mild pain with no other health problems: either may be used according to the label.

• Pain with swelling, such as a sprain or toothache: ibuprofen may help if it is suitable for you.

• Stomach ulcer history, kidney or heart disease, asthma sensitivity or taking blood thinners: paracetamol is more often suitable, but ask a pharmacist first.

• Cold and flu remedies: check the ingredients, because many contain paracetamol or ibuprofen already.

• Child, older adult, pregnant or breastfeeding: seek advice before choosing, since doses and suitability differ.

• Any suspected overdose: call NHS 111 or go to A&E immediately; do not wait for symptoms.

Paracetamol is not harmless in unlimited amounts, and ibuprofen is not safe just because it is sold on the shelf. A stronger-sounding product is not necessarily more effective. Taking extra when pain persists is a common cause of harm. And neither treats the underlying cause of persistent pain.

Another misconception is that you cannot take them with other medicines. Often you can, but interactions with ibuprofen are more common, so checking is worthwhile.