Recent headlines and statements by U.S. government officials have reignited questions and confusion about what causes autism spectrum disorder — and what doesn’t. On Sept. 21, President Donald Trump and members of his cabinet warned against taking acetaminophen (sold as Tylenol and other brands) during pregnancy, claiming it could increase the risk of autism.

Additionally, the U.S. Food and Drug Administration (FDA) announced it would add a warning label to acetaminophen products, cautioning a “possible association” between autism spectrum disorder and the use of acetaminophen during pregnancy.

The following day, the FDA announced it would begin a label update to a drug called leucovorin, designating it as a treatment of “autism symptoms” in a rare condition called cerebral folate deficiency. Leucovorin is a decades-old form of folic acid used to treat some types of cancer and anemia.

These claims have left many people anxious or unsure about what’s true. Here’s what the latest science says about autism, treatments, and these public concerns.

1. Autism Has Many Causes, Both Genetic and Environmental

Most health experts agree that autism is linked to a combination of genetic factors and environmental factors.

Studies have found that hundreds of different genes can influence how the brain develops, and changes in these genes are thought to be the main reason some people develop autism. This means that autism often runs in families, and having a sibling or parent with autism increases the chance of a diagnosis.

Scientists have also discovered that there isn’t just one “autism gene.” Instead, many different genes can be involved, and each person’s situation is unique.

Environmental factors may also play a role. These may include prenatal exposure to:

• Fever
• Certain infections, such as rubella and influenza
• Air pollutants, heavy metals such as lead and mercury, and pesticides
• Certain medications, including some antibiotics, antidepressants, and antiepileptic medications
• Gestational diabetes and maternal obesity

Other risk factors may include either parent being older in age, the use of certain assisted reproductive technologies, and the nutritional status of the mother.

However, decades of research show no single environmental factor — including the use of a particular medication or chemical — directly causes autism.

2. Health Experts Support Safe Use of Acetaminophen During Pregnancy

At the Sept. 21 press conference, Trump, along with Secretary of Health and Human Services Robert F. Kennedy Jr. and Administrator for the Centers for Medicare and Medicaid Services Dr. Mehmet Oz, repeatedly said that people should not take acetaminophen when they’re pregnant, suggesting doing so could cause autism.

“Taking Tylenol is not good. I’ll say it: It’s not good,” Trump said.

He went on to suggest that communities without access to the medicine have “no autism.”

What the Science Says About Acetaminophen and Autism

However, scientific research suggests otherwise. Recent large studies, including a 2024 study of nearly 2.5 million children in Sweden, haven’t found a strong or consistent link between acetaminophen use during pregnancy and autism or attention-deficit/hyperactivity disorder (ADHD) — especially when family factors are considered.

Large studies, including one with nearly 2.5 million children, haven’t found a strong or consistent link between acetaminophen use during pregnancy and autism.

A 2025 systematic review of 46 studies did find an association — but not causation — between prenatal acetaminophen exposure and neurodevelopmental conditions, including autism and ADHD. However, the review’s authors and other experts noted that these findings may be influenced by other factors (such as the genetic background and family environment of the participants and the health conditions acetaminophen was used to treat).

Most health experts agree that acetaminophen remains the safest choice for treating pain or fever during pregnancy when used as directed. Overuse of acetaminophen — such as taking high doses for long periods — can cause liver damage, but this is rare and usually linked to exceeding the recommended amount.

The American College of Obstetricians and Gynecologists (ACOG) affirmed on Sept. 22 that acetaminophen is still a safe, important option for treating pain and fever during pregnancy. Alternatives like nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, and naproxen sodium can carry risks, especially later in pregnancy.

The agency noted that conditions treated by acetaminophen, like fever and severe pain, are far more dangerous to pregnant people and their babies than any theoretical risks linked to the medicine itself.

ACOG recommends the use of acetaminophen only when needed, in the lowest effective dose, and that people always talk with their doctor if they have questions.

3. Leucovorin Is Not a Treatment for Autism

On Sept. 22, the FDA began a label update for leucovorin for treating cerebral folate deficiency. In this rare condition, people have symptoms that sometimes overlap with features of autism, including difficulties with social communication and sensory processing. Some children with confirmed cerebral folate deficiency may see improvements in these types of symptoms from leucovorin.

However, this treatment is only recommended in specific cases where cerebral folate deficiency is diagnosed by a doctor. Leucovorin is not recommended or proven for treating autism broadly, and it is not part of clinical guidelines for autism spectrum disorder.

How Is Autism Treated?

The main treatments for autism spectrum disorder are various types of therapy, not medication. These include:

• Behavioral therapies, such as applied behavior analysis, which help build communication, social, and daily living skills
• Speech therapy to improve communication skills
• Occupational therapy to support sensory, fine motor, and daily life skills
• Physical therapy for movement and coordination challenges
• Family and educational supports to help with social skills, classroom success, and home routines

There are no FDA-approved medications that treat the core features of autism itself.
However, some medicines can help with related symptoms. These include:

• Irritability and aggression — Medications like risperidone and aripiprazole are FDA approved to treat irritability and aggression in children and teens with autism spectrum disorder.
• Other symptoms — Doctors might also prescribe medicines to help with hyperactivity, anxiety, sleep problems, or seizures, if these are present.

There are no FDA-approved medications that treat the core features of autism itself.

Medicines can make it easier for children and adults with autism to participate in therapy and daily life, but they do not change the underlying autism diagnosis.

4. You Should Always Talk to Your Doctor About Medicines and Autism Concerns

If you have questions about autism or medications like acetaminophen, talk to your healthcare provider. Doctors can help you weigh risks and benefits based on the latest science and your individual situation. Never start or stop a treatment — for yourself or your child — without consulting a healthcare professional.

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On MyAutismTeam, people share their experiences with autism, get advice, and find support from others who understand.

Do you have questions about medications like acetaminophen or leucovorin and their connection to autism? Let others know in the comments below.