Is it safe to take acetaminophen (Tylenol) during pregnancy?

What's actually in it

Acetaminophen (sold as Tylenol and in many cold and pain formulas) is the most common pain reliever used during pregnancy. Doctors have long considered it the safest option, since aspirin and ibuprofen carry known risks. But recent research is raising new concerns.

Acetaminophen crosses the placenta and reaches the developing fetus. It has weak hormonal activity, which matters most during sensitive windows of development.

What the research says

A 2026 study in Reproductive Toxicology found that prenatal acetaminophen exposure disrupts neuroendocrine regulation in offspring. Specifically, it altered the hypothalamic-pituitary axis, the system that controls stress hormones, reproduction, growth, and metabolism.

The critical window was early pregnancy, when these neuroendocrine systems are forming. Exposure later in pregnancy or after birth showed much smaller effects. It was the timing that mattered most, not just the dose.

Other research has linked prenatal acetaminophen use to higher rates of ADHD, autism, and reproductive anomalies in children, though direct causation is still debated. The neuroendocrine disruption found in this study is a plausible biological pathway for those associations.

This doesn't mean you should never take it. But using acetaminophen only when genuinely needed, at the lowest effective dose, and for the shortest duration is a reasonable precaution.