Since it first appeared on UK shelves in 1956, paracetamol has become the nation’s default painkiller – swallowed for everything from headaches and toothache to back pain and fever.
An estimated 200 million packets are sold over the counter each year.
Cheap, widely available and generally safe when used correctly, it is a medicine cabinet essential for millions of Britons.
But despite its ubiquity, paracetamol remains one of the most misunderstood drugs we take.
Scientists still debate exactly how it works in the body. Its effectiveness for some common conditions has been questioned in recent years.
And while it is safe at recommended doses, it is also one of the leading causes of overdose-related hospital admissions in the UK.
That leaves patients with some surprisingly basic questions: Should you take it before pain strikes or wait until symptoms hit? How long is it safe to use? And is there any real benefit in paying more for branded versions over supermarket generics?
So how did this small white tablet become a household staple – and how safe is it, really?

Since it first appeared on UK shelves in 1956, paracetamol has become the nation’s default painkiller – swallowed for everything from headaches and toothache to back pain and fever
Dr Deborah Grayson, a pharmacist with 30 years of experience, tells the Daily Mail: ‘When it comes to precisely what paracetamol does and how it works, it’s a bit unclear.
‘It’s not uncommon for scientists not to fully understand how medicines work – particularly those that act on the nervous system.’
Unlike ibuprofen, which reduces inflammation at the site of injury, paracetamol works primarily in the brain and spinal cord. Researchers believe it dampens the production of chemical messengers involved in pain and temperature regulation, though the precise mechanism remains under debate.
‘It reduces the production of substances called prostaglandins, essentially inhibiting the enzymes responsible for transmitting pain signals,’ says Dr Grayson.
‘There is also some suggestion that it acts on the cyclooxygenase-2 (COX-2) pathway, which plays a key role in inflammation.
‘Ibuprofen inhibits this enzyme too, though paracetamol does not appear to have the same anti-inflammatory effect.
‘Instead, paracetamol seems to work mainly by blocking pain signals in the brain.’
Here, Dr Grayson reveals exactly what you need to know about paracetamol…
Is branded paracetamol better than supermarket own-brand generics
With prices ranging from 35p for a packet of supermarket own-brand paracetamol to £2.35 for the branded equivalent, is there any real difference?
‘Standard 500mg paracetamol tablets are essentially the same,’ says Dr Grayson, dubbed the ‘Godmother of Pharmacology’.
‘There may be subtle differences in the non-active ingredients, such as fillers, colourings and binding agents, but they should work in exactly the same way.’
She adds that although the active ingredient is identical, prices can vary significantly between brands due to packaging, marketing and advertising.
‘Generic tablets usually have simpler packaging and aren’t heavily advertised,’ she says.
Do cold and flu medicines work better than plain paracetamol?
Paracetamol is often the first-line over-the-counter treatment for fever, headaches and body aches associated with colds and flu.
Many brands also sell dedicated cold and flu products formulated with a combination of active ingredients – most commonly paracetamol and a decongestant.
These typically come with a much higher price tag than plain paracetamol.
For example, a packet of 16 Lemsip Max Day & Night Cold & Flu Relief capsules costs £6.80 at Boots – 43p per capsule. By comparison, 16 Boots 500mg paracetamol tablets cost just 49p, or around 3p per tablet.
So is there any real benefit to choosing a branded cold and flu remedy over standard paracetamol?
‘While decongestants can make you feel a little better in the short term, they can actually worsen symptoms over time,’ says Dr Grayson.
‘You can end up more congested than you were before taking them. From a cold and flu perspective, you’re usually better off taking regular paracetamol two to four times a day to control fever and ease pain.’
What does ‘maximum strength’ paracetamol actually mean?
Many paracetamol products are labelled ‘maximum strength’ – a term Dr Grayson says can be misleading.
‘When a product is labelled ‘max strength’, it simply means it contains 500mg of paracetamol per tablet,’ she explains. ‘That’s the same dose as standard ‘regular’ paracetamol.’
According to the NHS, the maximum recommended dose for adults is two 500mg tablets, up to four times in 24 hours.
The phrase is often used on cold and flu remedies that combine paracetamol with other ingredients. The danger is that people may take more than one type of cold medicine at the same time, not realising they are stacking their total paracetamol intake – increasing the risk of serious liver damage.
In reality, ‘maximum strength’ usually just indicates that the product contains the highest dose permitted for over-the-counter sale in a single tablet, rather than a more potent formulation.
Does rapid-release paracetamol work faster?
According to Dr Grayson, there is some scientific evidence behind ‘rapid-release’ tablets, such as Panadol Rapid.
These formulations are designed to provide faster pain relief than standard paracetamol, with studies suggesting they can begin working within 30 minutes.
‘Typically, manufacturers add ingredients such as sodium bicarbonate to rapid-release formulas, which helps the tablet dissolve more quickly in the gastrointestinal tract,’ she explains.
‘They can also micronise the active ingredient – meaning the particle size is made much smaller – so it passes across the gut wall more easily.’
This allows the paracetamol to reach the small intestine faster, where it is absorbed into the bloodstream.
‘The difference in speed is often marginal, though,’ Dr Grayson adds.
While standard paracetamol can take up to an hour to take effect, rapid-release – particularly effervescent forms – may begin working in around 30 minutes.
Why is caffeine added to paracetamol – and does it help?
Paracetamol is often combined with caffeine to enhance its pain-relieving effects.
According to Dr Grayson, caffeine can accelerate the absorption of paracetamol, helping it enter the bloodstream more quickly. It also acts on adenosine receptors in the brain, reducing the perception of pain.
This is why products marketed for period pain and migraines frequently contain caffeine alongside paracetamol.
Caffeine also acts as a vasoconstrictor, narrowing blood vessels – particularly in the brain – by blocking adenosine receptors, which would normally cause them to dilate.
This temporary narrowing can raise blood pressure slightly and reduce cerebral blood flow, which may help relieve certain types of headache.
What’s the difference between paracetamol and co-codamol?
Paracetamol is also available in combination with codeine in varying strengths. Lower-dose formulations – commonly known as co-codamol – can be bought over the counter at pharmacies, while higher-strength versions require a prescription.
When taken together, paracetamol and codeine work through complementary mechanisms.
Codeine is an opioid that binds to opiate receptors in the brain and spinal cord, reducing the transmission of pain signals. Paracetamol works through a different pathway, primarily within the central nervous system.
‘It’s like an additional mode of action on top of the paracetamol,’ says Dr Grayson.
Is paracetamol safer than ibuprofen?
‘Paracetamol is gentler on the stomach than ibuprofen, but it is far more dangerous in overdose because it can cause irreversible liver damage,’ says Dr Grayson.
‘This is because ibuprofen inhibits not only COX-2, but also COX-1.
‘COX-1 is an enzyme involved in producing mucin and bicarbonate in the digestive system.
‘Mucin forms the protective mucus lining of the stomach, while bicarbonate helps neutralise stomach acid.
‘If you inhibit COX-1, that protective barrier is weakened, meaning the stomach lining can effectively be digested by acid and pepsin.
‘So if you’re taking ibuprofen over a prolonged period, blocking that mechanism increases the risk of gastric irritation or even erosion.’

Why is there a limit on how much paracetamol you can buy in the UK?
Paracetamol overdose is a leading cause of acute liver failure.
Compared with the US, where paracetamol can be purchased in large quantities, the UK tightly regulates sales to reduce the risk of overdose.
General retail outlets can sell packs of 16 tablets or fewer, while pharmacies can sell up to 32, with a maximum of 100 tablets per transaction. This legislation was introduced in 1998 to help prevent self-poisoning.
Can taking paracetamol too often cause headaches?
‘All painkillers taken regularly carry the risk of an analgesic overuse headache, with opiates being the worst,’ says Dr Grayson.
‘Taking painkillers pre-emptively on a regular basis can increase the risk. For people with chronic pain, this may be unavoidable, but if you’re taking them to prevent pain, there’s a real danger of getting caught in a perpetual loop.’
What happens if you take too much paracetamol?
While safe at the recommended dose, taking too much paracetamol can cause serious harm and requires urgent medical attention.
‘Most people are now hopefully aware of the risks, and we generally see fewer accidental overdoses,’ says Dr Grayson.
‘However, some people assume the occasional extra dose is harmless. The risk is higher if your liver isn’t functioning well or if you drink large amounts of alcohol.’
A deliberate overdose is a medical emergency, even if the person feels well.
‘Symptoms such as nausea, vomiting and abdominal pain usually appear 24 to 72 hours after an overdose,’ explains Dr Grayson.
‘Over the following days, jaundice, confusion, extreme drowsiness, and liver or kidney damage can develop. If the overdose isn’t treated quickly, permanent liver damage – even cirrhosis – can occur.
‘That’s why restrictions on over-the-counter sales were introduced: to prevent people stockpiling large quantities of paracetamol.’

Speaking at the White House, President Trump told expectant mothers to ‘tough it out’ and ‘fight like hell’ not to take the drug, claiming it was contributing to rising rates of autism
Does paracetamol really cause autism?
In September, US health chiefs urged pregnant women to take paracetamol – known as Tylenol in America – sparingly, advising use at only ‘the lowest effective dose for the shortest possible time’.
Speaking at the White House, President Trump went further, telling expectant mothers to ‘tough it out’ and ‘fight like hell’ not to take the drug, claiming it was contributing to rising rates of autism.
The remarks sparked an international furore – not least because in many countries, including the UK, paracetamol is recommended as the first-line painkiller during pregnancy.
Around half of pregnant women in Britain are thought to take it at some point, rising to about 65 per cent in the US.
Since then, a major research paper published in The Lancet has found no evidence that paracetamol use in pregnancy causes harm when taken as directed.
Major health bodies worldwide – including the NHS, the World Health Organization and the American College of Obstetricians and Gynecologists (ACOG) – continue to state that paracetamol remains the safest and recommended option for pain relief during pregnancy when used appropriately.
















