The Myth That Circumcision Causes Autism

Why correlation is not causation—and how misinformation harms trust in medicine

The Evidence Room — Interrogating the research before it becomes “accepted truth.

Circumcision is a minor surgical procedure in which the foreskin covering the tip of the penis is removed. It is usually performed by physicians in hospitals or clinics shortly after birth, often using local anesthesia. In Jewish and Muslim traditions, circumcision carries deep religious meaning: a ritual of identity and covenant performed on the eighth day of life or during early childhood. In other settings, parents may choose it for hygiene, cultural, or preventive health reasons. When done properly, it is safe and brief, with rare complications.

In modern medical practice, circumcision is considered an optional procedure, not a medical necessity. Professional organizations like the American Academy of Pediatrics note that while there are potential health benefits—such as reduced risks of urinary tract infections and some sexually transmitted infections—these benefits are not strong enough to justify universal recommendation. Proper informed consent requires explaining this balance clearly: parents should know the procedure is elective, that local anesthesia and sterile technique are essential, and that they may freely decline without penalty or judgment.

The rumor that circumcision “causes” autism traces back mainly to one Danish study published in 2015. Researchers followed about 340,000 boys born between 1994 and 2003 to see if those who were circumcised later developed autism. Out of nearly 5,000 autism cases, only 57 occurred in circumcised boys. That means about 1.7 percent of circumcised boys were diagnosed with autism, compared with 1.4 percent of uncircumcised boys—a difference of roughly 3 extra cases per 1,000 children. Statistically, this produced a hazard ratio of 1.46, or a 46 percent relative increase. But in real-world terms, the difference was very small, and the authors themselves cautioned that their findings did not prove causation. They acknowledged that incomplete circumcision data, cultural differences, and unmeasured factors could easily explain the weak association.

The Danish team speculated about a possible mechanism, suggesting that pain or stress from circumcision might influence later brain development. They referred to animal research showing that early pain can affect later stress responses. However, these were theoretical ideas, not observed findings. The study did not measure pain, anesthesia type, or emotional responses. It also did not record whether infants received any pain medication after circumcision. In Denmark, newborns typically receive local anesthesia, not Tylenol/acetaminophen for circumcision. The researchers’ discussion of “pain-induced stress” was a hypothesis only, not evidence from their data.

For years, rumors have circulated online that male circumcision might “cause” autism. The idea resurfaces every few months, often in social media posts or pseudoscientific blogs citing obscure studies or misinterpreted data. The claim sounds alarming, but it falls apart under even modest scientific scrutiny. It’s a perfect case study in how weak evidence, confirmation bias, and emotional rhetoric can combine to mislead the public and damage confidence in legitimate science.

In recent years, some public figures have further distorted this study’s findings. Robert F. Kennedy Jr., in particular, has claimed that circumcision may lead to autism because of exposure to Tylenol (acetaminophen/paracetamol) used for pain relief. This statement is both scientifically baseless and factually wrong. It is also a lie when spoken by someone who holds or seeks to hold the nation’s highest public health office.

Let’s be clear: Kennedy’s attempt to link circumcision with autism is not just bad science, it’s ugly politics. This isn’t a new idea; it’s an old prejudice dressed up in modern language. For centuries, circumcision has been the pretext for vilifying Jews, often under the banner of “medical concern.” To revive that narrative now—claiming to “just ask questions”—isn’t intellectual curiosity, it’s coded bigotry. Turning a core religious practice into a supposed public-health threat doesn’t protect children, it stigmatizes families. When misinformation plays on ancient stereotypes, it crosses a moral line.

The 2015 Danish paper he cited never mentioned Tylenol, acetaminophen, or any other pain medication, nor did it collect or analyze any data on drug exposure. The authors speculated only about stress and pain as hypothetical factors, not medications. Linking a study that never measured or mentioned Tylenol/acetaminophen to claims about autism is a deliberate misrepresentation—an abuse of public trust that turns scientific uncertainty into political theater.

According to both the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG), circumcision must never be performed without pain control. The recommended methods are injected local anesthesia, either a dorsal penile nerve block or a subcutaneous ring block using 1% lidocaine without epinephrine. These techniques provide the most effective relief and are considered the standard of care. Topical creams such as EMLA (lidocaine–prilocaine) may be added but are less effective on their own. Comfort measures like oral sucrose, swaddling, or pacifier use can supplement anesthesia but should never replace it. After the procedure, acetaminophen may be used if needed but it rarely is.

Autism spectrum disorder (ASD) is a neurodevelopmental condition with a complex, multifactorial origin involving genetics, prenatal environment, and possibly some early-life exposures. Despite decades of research, no credible evidence connects circumcision—an ancient surgical practice involving removal of the foreskin—to the development of autism. Yet a few small, flawed studies have made this leap, and anti-circumcision activists have been quick to amplify them.

The circumcision-autism myth also capitalizes on a genuine ethical conversation: whether routine neonatal circumcision should be done for cultural, religious, or medical reasons. That is a legitimate debate. But to conflate an ethical question about autonomy and consent with a false claim of neurological harm is irresponsible. Ethical reasoning requires facts; misinformation undermines autonomy by distorting choice.

Biologically, the claim makes little sense. Circumcision removes skin tissue from the penis under local or regional anesthesia, typically in infancy. There is no known pathway connecting this minor surgical event to brain development months or years later. If surgery or pain exposure in infancy caused autism, we would expect similar findings in children undergoing hernia repairs, cardiac procedures, or other operations—which we do not. Moreover, autism begins developing before birth, with brain differences identifiable in utero. Linking it to a postnatal skin procedure ignores what we know about neurodevelopment.

Some proponents cite the “stress” of circumcision as the mechanism, arguing that early pain could alter neurochemistry. Yet studies on neonatal stress and long-term outcomes show that infants exposed to brief, well-managed procedures do not develop autism or any comparable neurological syndrome. Hospitals routinely use anesthesia and sucrose analgesia to minimize discomfort. The real stressor here is often misinformation itself, which can generate anxiety, guilt, and mistrust among parents.

This myth’s persistence highlights a deeper issue: the public’s limited understanding of epidemiologic research. “Correlation” means two things occur together; it doesn’t mean one caused the other. Ice cream sales and drowning deaths both rise in summer, but one doesn’t cause the other. Circumcision and autism rates can overlap geographically or demographically without any causal link. A proper test of causation requires plausible mechanisms, dose-response effects, replication across populations, and biological consistency—all of which are absent here.

Ethically, physicians have an obligation to correct misinformation, even when it comes cloaked in scientific language. The harm is not theoretical. Parents frightened by false claims may avoid safe procedures, distrust vaccines, or turn to unproven therapies. Misinformation spreads faster than science because it offers certainty where data offer nuance. For clinicians, explaining why a study is weak can be more difficult than repeating a myth—but that’s part of our professional duty.

A more constructive discussion would focus on informed consent and shared decision-making in circumcision. Parents should understand the real risks and benefits: small chances of bleeding or infection, protection against some infections later in life, and deeply personal cultural or religious factors. Those are evidence-based conversations worth having. Autism is not part of that equation.

The circumcision-autism narrative should serve as a warning about how easily statistical noise can become public panic. It also reminds us that ethical medicine depends on public literacy. When people cannot distinguish a correlation from a cause, pseudoscience fills the vacuum. Rebuilding that literacy means teaching patients and the public not just what studies show, but how to think critically about what they do not show.

Reflection / Closing:
Misinformation often thrives in the spaces where ethics and science overlap. It is our job to close those spaces with clarity, humility, and truth. As clinicians, we must not only heal but also explain—because when medicine stays silent, superstition speaks louder.