Tylenol and Autism: What Pregnancy Research Really Shows

Does taking Tylenol in pregnancy cause autism? The best evidence says no. Some older studies found a small link between Tylenol and autism, but the strongest studies, which compare brothers and sisters from the same family, found no link at all [1][2]. Acetaminophen (called paracetamol in the UK) is still the recommended medicine for pain and fever in pregnancy in the US and UK.

Why people asked about Tylenol and autism

Over the years, several observational studies found that children whose mothers used acetaminophen in pregnancy were a little more likely to be diagnosed with autism or ADHD. Observational studies watch what happens in real life. So they can show a link, but they cannot prove that one thing causes another.

One often-cited 2020 study from the Boston Birth Cohort measured acetaminophen markers in cord blood from 996 babies. Children in the highest group had higher odds of an autism diagnosis [3]. But the autism group was small, with only 66 children, and the authors said the design could not prove cause [3].

The 2021 consensus statement

In 2021, a group of scientists led by Ann Bauer published a consensus statement in Nature Reviews Endocrinology. It was supported by 91 scientists, doctors and public health experts [4]. They called for “precautionary action,” not total avoidance. They advised using acetaminophen only when medically needed, at the lowest effective dose for the shortest possible time, and asking a doctor or pharmacist before long-term use [4].

In August 2025, a review led by researchers including Andrea Baccarelli looked at 46 studies and said the evidence supported a link with neurodevelopmental conditions [5]. The review itself noted that sibling-controlled studies mostly found no link [5]. News reports later showed that Dr Baccarelli had been paid at least $150,000 as an expert witness for families suing the maker of Tylenol. A US federal judge had excluded his testimony in that case [6]. This does not make the review wrong, but it is a conflict of interest.

The Tylenol autism study that compared siblings

The biggest problem with early studies is confounding, where another factor explains both the medicine use and the outcome.

Sibling studies compare a child who was exposed to acetaminophen in pregnancy with a brother or sister who was not. Siblings share many genes and much of their family life. If the medicine itself caused autism, the exposed sibling should still have a higher risk.

In 2024, Ahlqvist and colleagues published this kind of study in JAMA. They followed 2,480,797 children born in Sweden from 1995 to 2019. About 7.49% were exposed to acetaminophen in pregnancy [1].

• Whole population. Without sibling comparison, there was a very small rise in autism risk (hazard ratio 1.05) [1].
• Siblings compared. When full siblings were compared, the link disappeared (hazard ratio 0.98, meaning no difference) [1].
• No dose pattern. Higher use was not linked to higher risk in the sibling analysis [1].

Confounding: fever, illness, family and genes

• Why the medicine was taken. People take acetaminophen because they have a fever, an infection, a headache or pain. Doctors call this “confounding by indication.” A 2021 review found that fever in pregnancy was itself linked to a slightly higher chance of autism [7]. So the illness, not the medicine, may explain part of the link.
• The parent’s own health. Long-term pain, migraine or anxiety can mean more medicine use, and some of these conditions run in families.
• Genes. Autism is strongly genetic. A large Swedish family study estimated that about 83% of the variation in autism risk comes from genetic factors [8]. Genes shared by a parent and child can affect both the parent’s health and the child’s development.

The lead author of the 2026 Lancet review said earlier links were likely explained by “genetic predisposition or other maternal factors such as fever or underlying pain” [2]. You can read more about this in our guide to what causes autism and our page on genetic testing for autism.

What happened in September 2025

On September 22, 2025, the US Department of Health and Human Services (HHS) held a press conference about autism. The HHS fact sheet said chronic acetaminophen use in pregnancy “may cause long-term neurological effects.” It also said the evidence “does not definitively establish causality” [9].

On the same day, the US Food and Drug Administration (FDA) said it had started the process for a label change on acetaminophen products [10]. It also sent a notice to physicians. The notice suggested doctors “consider minimizing” acetaminophen for routine low-grade fevers in pregnancy. It also said “a causal relationship has not been established and there are contrary studies” [11]. The FDA noted that acetaminophen is the only over-the-counter medicine approved for fever in pregnancy, and that high fevers in pregnancy can pose a risk to the baby [10].

The same announcement included leucovorin, a form of folate. The FDA started the process to label it for cerebral folate deficiency, a rare condition that can include autistic features. The FDA said more studies were needed for wider use [12]. Our page on leucovorin (folinic acid) for autism explains this in detail.

As of a September 2026 report, the Tylenol label had not actually changed [13].

How medical groups responded

• ACOG (US obstetricians). Its president said no reputable study has shown that acetaminophen in any trimester causes neurodevelopmental disorders. ACOG said untreated fever and pain can be harmful in pregnancy [14].
• SMFM (US maternal-fetal medicine specialists). SMFM said acetaminophen remains an appropriate medicine for pain and fever in pregnancy and that research has not established a causal relationship [15].
• MHRA (UK medicines regulator). The MHRA said there is no evidence that paracetamol in pregnancy causes autism. It said paracetamol remains the recommended pain relief when used as directed, and that untreated pain and fever can harm the baby [16].
• NHS. The NHS repeats the MHRA advice and asks you to check with a pharmacist, midwife or GP before taking any medicine in pregnancy [17].
• WHO. The World Health Organization said there is “currently no conclusive scientific evidence” confirming a link between acetaminophen in pregnancy and autism [18].

New Tylenol and autism research in 2026

Lancet review, January 2026

A systematic review and meta-analysis in The Lancet Obstetrics, Gynaecology, and Women’s Health looked at 43 studies, with 17 combined in the main analysis [2]. In sibling comparisons, there was no link with autism (odds ratio 0.98), ADHD or intellectual disability. The authors said the review had no funding and they had no competing interests. They also noted limits: only a few sibling studies exist, and many studies relied on self-report [2].

Danish study, JAMA Pediatrics, April 2026

Researchers in Denmark used national records for 1,506,155 children born from 1997 to 2022 [19][20]. They found no clear link between acetaminophen prescriptions in pregnancy and autism, including in sibling analyses. One limit is that the study only counted prescriptions, not medicine bought over the counter [20].

Hong Kong study, JAMA Internal Medicine, June 2026

This study used health records for 708,020 mothers and children in Hong Kong. In the sibling analysis of 124,333 children, the risk of autism was the same whether or not the child was exposed (hazard ratio 1.00) [21]. Acetaminophen taken before pregnancy was also linked to autism in the general analysis. A medicine taken before pregnancy cannot affect the baby, so this points to family factors, not the drug [21].

A study with mixed results

Not every study is simple. A March 2026 Taiwan study of 2,092,926 births found links in the full group but not overall in sibling analyses. Results differed by which sibling was exposed, so the authors drew no firm conclusions [22]. You can follow updates on our latest autism research page.

Is Tylenol in pregnancy safe? What you can do

If you are pregnant or planning a pregnancy, here are practical steps based on current advice [4][14][16].

• Do not stop needed treatment. If you have a fever or real pain, treating it matters. Untreated fever and pain can harm you and your baby.
• Use the lowest effective dose for the shortest time. Follow the package directions. Do not take more than the label says.
• Check combination products. Many cold and flu medicines contain acetaminophen, so read labels to avoid a double dose.
• Avoid swapping to other painkillers on your own. Medicines like ibuprofen and aspirin have known risks in pregnancy [10].
• Talk to your doctor or midwife if you need pain relief for more than a few days or have a high fever.

Questions to ask your doctor or midwife

• Do I need medicine for this, or can I try other things first?
• What dose is right for me, and for how many days?
• When should I call you about a fever?

When to talk to a professional

Call your doctor, midwife or maternity unit straight away if you are pregnant and have a high fever, a fever that will not come down, a severe headache, or pain that is not easing. In the US, call 911, and in the UK, call 999 for an emergency. For non-urgent UK questions, call NHS 111.

Worried about your child’s development? Talk to their doctor or health visitor. Our guide on what to do after an autism diagnosis can help with next steps.

A word about guilt

Many parents felt guilt after the 2025 news. If you took Tylenol for a fever or headache while pregnant, you did what doctors recommended. The best current evidence does not show that it caused your child’s autism. Your autistic child is not the result of something you did wrong.

Frequently asked questions

Does Tylenol in pregnancy cause autism?

The best current evidence says no. Some studies found a small link, but large studies that compare siblings from the same family found no difference in autism risk. This suggests the earlier link came from other factors, such as illness, fever or genes. Major groups including ACOG, the UK MHRA and the WHO say there is no proof that acetaminophen in pregnancy causes autism.

Is Tylenol safe to take while pregnant?

Acetaminophen is still the recommended medicine for pain and fever in pregnancy in the US and UK. Use it only when you need it, at the lowest dose that works, for the shortest time. Always follow the package directions. If you need it for more than a few days, or you have a high fever, speak to your doctor, midwife or pharmacist for advice.

Did the FDA change the Tylenol label in 2025?

In September 2025, the FDA said it had started the process for a label change and sent a notice to doctors. The notice also said a causal link had not been proven. As of a September 2026 news report, the actual Tylenol label had not changed and still told pregnant people to ask a health professional before using it.

What about paracetamol and pregnancy in the UK?

In the UK, acetaminophen is called paracetamol. The MHRA, the UK medicines regulator, said there is no evidence that paracetamol in pregnancy causes autism. It remains the recommended pain relief for pregnant women when used as directed. The NHS suggests checking with a pharmacist, midwife or GP before taking any medicine while pregnant.

I took Tylenol in pregnancy and my child is autistic. Is it my fault?

No. Autism is strongly linked to genes and early brain development. Large studies comparing siblings found that acetaminophen in pregnancy did not raise autism risk. Treating a fever or pain was a sensible, recommended choice. Worry is natural, but the evidence does not support blaming yourself. Your energy is best spent on supporting your child as they are.

References

1. Ahlqvist VH, Sjoqvist H, Dalman C, et al. Acetaminophen use during pregnancy and children’s risk of autism, ADHD, and intellectual disability. JAMA. 2024;331(14):1205-1214. doi:10.1001/jama.2024.3172. Link
2. D’Antonio F, Flacco ME, Della Valle L, Prasad S, Manzoli L, Samara A, Khalil A. Prenatal paracetamol exposure and child neurodevelopment: a systematic review and meta-analysis. Lancet Obstet Gynaecol Womens Health. Published online January 16, 2026. doi:10.1016/S3050-5038(25)00211-0. Link
3. Ji Y, Azuine RE, Zhang Y, et al. Association of cord plasma biomarkers of in utero acetaminophen exposure with risk of attention-deficit/hyperactivity disorder and autism spectrum disorder in childhood. JAMA Psychiatry. 2020;77(2):180-189. doi:10.1001/jamapsychiatry.2019.3259. Link
4. Bauer AZ, Swan SH, Kriebel D, et al. Paracetamol use during pregnancy: a call for precautionary action. Nat Rev Endocrinol. 2021;17:757-766. doi:10.1038/s41574-021-00553-7. Link
5. Prada D, Ritz B, Bauer AZ, Baccarelli AA. Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology. Environ Health. 2025;24:56. doi:10.1186/s12940-025-01208-0. Link
6. Scripps News. Scientist behind autism study cited by Trump admin paid $150K by plaintiffs suing Tylenol manufacturer. September 24, 2025. Link
7. Antoun S, Ellul P, Peyre H, et al. Fever during pregnancy as a risk factor for neurodevelopmental disorders: results from a systematic review and meta-analysis. Mol Autism. 2021;12:60. doi:10.1186/s13229-021-00464-4. Link
8. Sandin S, Lichtenstein P, Kuja-Halkola R, Hultman C, Larsson H, Reichenberg A. The heritability of autism spectrum disorder. JAMA. 2017;318(12):1182-1184. doi:10.1001/jama.2017.12141. Link
9. US Department of Health and Human Services. Autism announcement fact sheet. September 22, 2025. Link
10. US Food and Drug Administration. FDA responds to evidence of possible association between autism and acetaminophen use during pregnancy. Press announcement, September 22, 2025. Link
11. US Food and Drug Administration. Notice to physicians on the use of acetaminophen during pregnancy. September 22, 2025. Link
12. US Food and Drug Administration. FDA takes action to make a treatment available for autism symptoms. Press announcement, September 22, 2025. Link
13. Medical Daily. Nearly a year after the FDA moved to add a Tylenol pregnancy warning, the label has not changed. September 9, 2026. Link
14. American College of Obstetricians and Gynecologists. ACOG affirms safety and benefits of acetaminophen during pregnancy. Statement, September 22, 2025. Link
15. Society for Maternal-Fetal Medicine. SMFM response to administration announcement on acetaminophen use during pregnancy and autism. September 22, 2025. Link
16. Medicines and Healthcare products Regulatory Agency. MHRA confirms taking paracetamol during pregnancy remains safe and there is no evidence it causes autism in children. GOV.UK, September 22, 2025. Link
17. NHS. Medicines in pregnancy. NHS website. Link
18. World Health Organization. WHO statement on autism-related issues. September 24, 2025. Link
19. Prahm KP, Chen P, Rode L, et al. Acetaminophen exposure during pregnancy and the risk of autism in offspring. JAMA Pediatr. 2026;180(6):687-690. doi:10.1001/jamapediatrics.2026.0646. Link
20. Contemporary OB/GYN. Danish study finds acetaminophen exposure not associated with increased autism risk. 2026. Link
21. Luo S, Gong Q, Ai Y, et al. Prenatal acetaminophen (paracetamol) use and the risk of autism and/or attention-deficit/hyperactivity disorder among sibling-matched cohorts. JAMA Intern Med. 2026;186(9):1102-1111. doi:10.1001/jamainternmed.2026.2215. Link
22. Lee PC, Chuang YH, Hu YH, et al. Maternal acetaminophen use and child neurodevelopment. JAMA Pediatr. 2026;180(5):527-534. doi:10.1001/jamapediatrics.2026.0071. Link

Professional review: this guide is waiting for review by a qualified clinician. It was written and checked against the published sources listed above. How we check our guides.

This guide is general education, not medical advice. Always talk to your child’s doctor or care team. Last checked: October 2026.