There is no scientific evidence that Miralax (polyethylene glycol 3350) causes autism. This concern has circulated among parent communities but is not supported by peer-reviewed research.

Where the Concern Comes From

Some parents noticed behavioral changes in their autistic children when taking Miralax and attributed the medication as a contributing factor. The FDA received reports of neuropsychiatric side effects associated with PEG 3350 use in children, prompting a safety review. However, these reports were anecdotal, and the review did not establish a causal connection to autism.

Why Many Autistic Children Take Miralax

Constipation is extremely common in autistic children, affecting an estimated 30-40%. Restricted diets, sensory-related food selectivity, withholding behaviors, and possibly gut microbiome differences all contribute. Miralax is one of the most commonly prescribed treatments for pediatric constipation. The fact that many autistic children use Miralax reflects a pre-existing condition, not a causal pathway.

What Research Shows

Autism develops during prenatal brain formation, long before a child would take Miralax. No biological mechanism has been proposed or demonstrated by which PEG 3350 could cause autism. The temporal overlap of GI treatment and autism recognition in early childhood creates an apparent but coincidental association.

Managing GI Issues in Autism

Constipation and other GI issues should be treated proactively. Work with your pediatrician to find an appropriate treatment plan. Address feeding selectivity through ABA-based feeding therapy. Untreated GI discomfort can worsen behavior and reduce quality of life.