World's most popular painkiller may increase risk of 2 serious conditions

The painkiller most commonly taken by pregnant women may be linked to a greater risk of autism and ADHD in children, new research suggests. Paracetamol - also known as acetaminophen and widely sold under the brand name Tylenol in the US - has long been considered a safe option for expectant mothers dealing with headaches, fever, or minor pain.

It is even listed by the NHS as the first choice of treatment during pregnancy, provided it is taken in low doses and only for short periods. But a fresh analysis led by scientists from Harvard University and Mount Sinai in New York has raised concerns about its potential impact on child development.

The team reviewed 46 studies involving more than 100,000 participants, making it the largest and most detailed investigation into the issue to date.

The findings, published in the journal Environmental Health, suggest a “strong” association between prenatal exposure to paracetamol and higher rates of both autism and ADHD. While the research does not prove the drug directly causes these conditions, experts say the evidence is now compelling enough to warrant caution.

Dr Didier Prada, assistant professor of population health science at Mount Sinai, said: “Our findings show that higher-quality studies are more likely to demonstrate a link between prenatal acetaminophen exposure and increased risks of autism and ADHD. Given the widespread use of this medication, even a small increase in risk could have major public health implications.”

Around half of all pregnant women in the UK are believed to use paracetamol, compared with roughly two-thirds in the US. With such high usage rates, health specialists are urging mothers-to-be to take the drug only when essential and always under medical supervision. The advice is to use the lowest effective dose for the shortest possible time.

The researchers emphasised that women should not abruptly stop using paracetamol if advised by a doctor, since untreated fever or severe pain during pregnancy can itself harm a baby. Instead, the study highlights the importance of consulting healthcare professionals about safe alternatives and non-drug approaches where possible.

The new warning comes at a time when autism and ADHD diagnoses are climbing sharply in both the UK and US. NHS data shows nearly 130,000 children were on waiting lists for an autism assessment in England at the end of 2024, while prescriptions for ADHD medication have risen by 20 per cent in just a year.

While many researchers point to greater awareness and improved diagnostic methods as factors behind the increase, others argue that environmental and biological influences may also be contributing.