Can Tylenol Use During Pregnancy Cause Autism? What We Know (and What We Don’t)

For decades, doctors have recommended acetaminophen, best known by the brand name Tylenol, as the safest option for relieving pain or fever during pregnancy. Over-the-counter alternatives like ibuprofen and aspirin carry well-documented risks for the fetus.

That longstanding recommendation has come under scrutiny after comments from President Trump and the U.S. Food and Drug Administration (FDA).

The Claim: Tylenol Use During Pregnancy Raises Autism Risk

At a White House press briefing on September 22, President Trump linked Tylenol use to rising autism rates.

In a press release issued the same day, FDA commissioner Marty Makary, MD, MPH, stated that the agency was taking action “to make parents and doctors aware of a considerable body of evidence about potential risks associated with acetaminophen.”

Dr. Makary noted, however, that “It remains reasonable for pregnant women to use acetaminophen in certain scenarios, particularly when untreated fever or pain could cause harm.”

Several healthcare professional groups, including those from the American College of Obstetricians and Gynecologists (ACOG), have expressed concern that the administration’s announcement is causing unnecessary fear.

What We Know About Tylenol Use During Pregnancy

Acetaminophen is the only over-the-counter pain reliever broadly considered safe to use during pregnancy. About 2 out of every 3 American women will use acetaminophen during pregnancy, says Hugh Taylor, MD, chair of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine and chief of obstetrics and gynecology at Yale New Haven Hospital in Connecticut.

Doctors already recommend using Tylenol sparingly during pregnancy, but Dr. Taylor emphasizes it is often necessary. The most common reason is fever, which can be detrimental to the mother and developing fetus. “Taking acetaminophen to bring down a fever can actually have benefits and help avoid problems,” he says.

Anne R. Waldrop, MD, maternal-fetal medicine specialist and clinical assistant professor at Stanford Medicine in California, agrees. “Untreated maternal fever is not harmless and can lead to obstetric complications.”

A doctor may also recommend using Tylenol sparingly for other issues during pregnancy. “Immobility because of pain, or stress because of pain, can cause problems, too,” Dr. Waldrop says.

What Does Research Say About Tylenol Use During Pregnancy and Autism?

“Acetaminophen is well studied and proven to be safe for use in pregnancy as directed, including in the first trimester,” says Waldrop.

Siblings grow up in the same environments and share similar genetic traits. By comparing the health outcomes of siblings, scientists can draw stronger conclusions than if they were just looking at a broad population, because there are fewer unknown variables that could affect the results.

While initial statistical models of the two million kids showed a slight increase in autism prevalence among all women who used Tylenol during pregnancy, that link disappeared when the scientists compared outcomes for siblings, Waldrop says. In other words, when researchers compared siblings — one who had been exposed to Tylenol and one who was not — they found no increased risk of a later autism diagnosis.

Of the 46 studies, 27 found a link, 9 found no association, and 4 found that acetaminophen appeared to provide a protective effect against autism.

The authors of the sibling study said it makes sense that observational studies could find a link between Tylenol and conditions like autism and ADHD, because there are more unmeasurable differences between participants in population studies.

This is always a shortcoming of observational studies: While they can suggest patterns, they cannot separate the effect of a drug from the effect of the underlying reason for its use, or from genetic and familial traits, Waldrop says — a concept researchers often frame as “correlation versus causation.”

Just because two things happen together (correlation) — including acetaminophen use in pregnancy and a later autism diagnosis — doesn’t mean one causes the other (causation).

An often cited example is that ice cream sales and drowning accidents often go up at the same time; that’s what you call a link, association, or correlation. However, that doesn’t mean eating ice cream causes drowning. The actual reason is that both tend to happen more in the summer, when the weather is hot. This shows how two things can be linked (correlated) without one actually causing the other.

In the case of Tylenol and autism, factors like genetics, maternal health conditions, or medical issues that require taking the medication, may explain the connection. That’s why experts emphasize that the current evidence does not prove that acetaminophen causes autism.

The gold standard of research — randomized, placebo-controlled clinical trials — would be needed to offer credible evidence of causation. But that kind of study isn’t possible when it comes to pregnancy because it would be unethical to expose fetuses to a potentially harmful substance, says Waldrop.

What We Know About Causes of Autism

• Pregnancy after age 35 or within 12 months of having another baby
• Health issues during pregnancy such as gestational diabetes or bleeding
• The use of certain medications, including valproic acid capsules (used to control seizures in people with epilepsy).
• Smaller-than-expected fetal size or reduced oxygen to the fetus during pregnancy.
• Premature birth

Many gene variations appear to have a link to autism. Researchers are still learning about the genetic causes of the condition.

“Research suggests that the rise in autism diagnoses reflects improved awareness, broader diagnostic criteria, and better access to services,” says Elizabeth Laugeson, PsyD, a clinical professor of pediatric psychology at UCLA in California.

Should You Avoid Tylenol During Pregnancy?

Waldrop agrees there’s no available evidence that’s strong enough to change what experts have been recommending for years. “The balance of evidence still supports acetaminophen as an important and appropriate therapy in pregnancy,” she says.

The bottom line, according to Taylor: “Don’t take acetaminophen if you don’t need it. But if you do, it remains the best option, especially if you have a fever. Use the lowest effective dose, for the shortest time necessary, and talk with your healthcare provider about any concerns.”