Landmark trial finds acetaminophen and ibuprofen safe for babies in first year with no link to eczema or bronchiolitis

A large multicentre randomised controlled trial conducted in New Zealand has found that acetaminophen (also known as paracetamol) and ibuprofen are equally safe for use in infants during the first year of life, with no evidence linking either medication to eczema or bronchiolitis.

The PIPPA Tamariki study enrolled 3,923 infants younger than 8 weeks between April 2018 and July 2023 across sites in Auckland and Wellington. After withdrawals, 3,908 infants were included in the intention-to-treat analysis: 1,985 assigned to receive only paracetamol and 1,923 assigned to receive only ibuprofen as required for fever or pain until age 1 year, according to dosing guidelines from the New Zealand Formulary for Children (The Lancet Child & Adolescent Health).

Parents were surveyed regularly about symptoms, and researchers reviewed prescribing data and hospital records. Eczema, defined by UK Diagnostic Criteria or hospitalisation, occurred in 322 (16.2%) of infants in the paracetamol group and 296 (15.4%) in the ibuprofen group (absolute risk difference 0.8%, 95% CI –1.5 to 3.1; p=0.48). Hospitalisation for bronchiolitis (including viral-induced wheeze or asthma) occurred in 98 (4.9%) versus 82 (4.3%) infants respectively (absolute risk difference 0.7%, 95% CI –0.6 to 2.0; p=0.32), the trial report states (The Lancet Child & Adolescent Health).

Nineteen serious adverse events were reported in 17 participants (0.4% paracetamol group, 0.5% ibuprofen group); none were attributed to the trial medications (University of Auckland).

“Our study found that paracetamol and ibuprofen are incredibly safe to use in young children,” said lead researcher Professor Stuart Dalziel, Cure Kids Chair of Child Health Research at the University of Auckland and paediatrician at Starship Children’s Hospital. “These results give parents and health professionals high confidence to continue to use these important medications,” he stated in the university announcement (University of Auckland).

Earlier observational studies had suggested possible associations between early-life paracetamol exposure and later eczema, wheeze or asthma. This trial is the first randomised controlled trial—the gold standard for establishing causality—to directly compare the two medications on these outcomes in the first year of life (ScienceDaily).

The findings, published in January 2026 in The Lancet Child & Adolescent Health, represent the initial results of the larger PIPPA Tamariki project (Paracetamol and Ibuprofen in the Primary Prevention of Asthma in Tamariki). It is the largest clinical trial involving children ever conducted in New Zealand. Participants continue to be followed until age six, with planned analyses at ages three and six to examine longer-term outcomes including asthma, hay fever, and developmental conditions such as autism and ADHD, which are more reliably diagnosed later in childhood (EurekAlert).

“We know that two-thirds of children who are wheezy at age three years don’t develop asthma by age six,” Dalziel noted. “Thus we need to wait until school age to ultimately test if paracetamol in the first year of life causes asthma.” Lead author Dr Eunicia Tan, senior lecturer at the University of Auckland and emergency physician at Middlemore Hospital, added that the full study will provide important evidence on links to asthma, eczema, hay fever and developmental disorders (University of Auckland).

The trial was funded by the Health Research Council of New Zealand and Cure Kids, and conducted by the University of Auckland and the Medical Research Institute of New Zealand. Both medications remain widely used worldwide for fever and pain in infants when administered according to guidelines.