Lancet umbrella review finds no causal link between paracetamol and neurodevelopmental disorders

A major umbrella review published in The Lancet concludes that paracetamol (acetaminophen, sold as Tylenol in the United States) taken during pregnancy is safe when used as recommended and does not cause autism spectrum disorder, attention-deficit/hyperactivity disorder, or intellectual disability in children. The finding adds weight to other large analyses and alters the tone of a debate that prompted regulatory caution and public alarm over the past year.

Grainne McAlonan, a translational neuroscience professor at King’s College London, summarized the review’s central finding: “confirmed that there is no relationship between taking paracetamol in pregnancy and a higher likelihood of autism, ADHD, or intellectual disabilities in the offspring,” and expressed hope the results “bring the matter to a close.” Her comments reflect the review’s careful, broad appraisal of available studies and its conclusion that current evidence does not establish causation.

The Lancet assessment arrives after a string of high‑profile and sometimes conflicting studies. A rapid review published in The BMJ last November judged the quality of studies claiming links to be low to critically low and found no clear association. A separate multinational analysis of more than 2 million Swedish children published in JAMA likewise reported no link, while acknowledging limits such as reliance on prescriptions and self‑reports that may undercount over‑the‑counter use. Across multiple cohorts, sibling comparison analyses have been especially influential; when pregnancies are compared within the same family, small associations seen in general population studies often vanish, suggesting familial or genetic confounding rather than a direct drug effect.

The scientific reassessment follows regulatory actions taken in 2025. In September that year the U.S. Food and Drug Administration initiated a label change and alerted physicians about a possible association between prenatal acetaminophen exposure and neurodevelopmental outcomes. The American College of Obstetricians and Gynecologists has since reiterated that acetaminophen remains the safest first‑line analgesic and antipyretic in pregnancy and that no change in clinical practice is warranted based on current evidence.

Experts caution that limitations persist. Many studies use self-reported medication histories or prescription databases that can miscount actual over‑the‑counter use and dosage. Confounding by indication, where the underlying reason for taking medication, such as fever or infection, may itself affect neurodevelopment, remains difficult to eliminate entirely. Reviewers and investigators call for continued high‑quality, prospective research that can better separate genetic and environmental contributors to developmental disorders.

Clinicians and public health authorities also underscore the clinical risks of avoiding acetaminophen. Alternatives such as nonsteroidal anti‑inflammatory drugs and opioid analgesics carry known harms in pregnancy, including risks to fetal renal function, amniotic fluid levels, and other adverse outcomes. Fever control with acetaminophen is itself protective against some birth defects, reinforcing the drug’s role in maternal care.

For now, the converging conclusions from The Lancet, The BMJ and large population studies support continuing judicious use of acetaminophen in pregnancy. Researchers say the door remains open for more definitive work, but they hope the latest synthesis will reduce confusion and prevent unintended harms from restricting a widely used, generally safe option for pregnant patients.