Autism-related class action lawsuits have become a significant and complex wave of litigation in the United States, but whether they represent the largest lawsuit wave in U.S. history depends on how one measures size—by number of plaintiffs, scope, or impact. In recent years, multiple large-scale lawsuits have emerged, particularly focusing on alleged causes of autism spectrum disorder (ASD) and related conditions such as ADHD, involving products like acetaminophen (Tylenol) and baby food brands.
One of the most prominent waves involves the acetaminophen autism lawsuits consolidated into a multidistrict litigation (MDL) in the Southern District of New York. This MDL, created in late 2022, centralized hundreds of lawsuits alleging that prenatal exposure to acetaminophen caused autism or ADHD. The litigation has been fast-moving and aggressive, with courts holding rigorous scientific hearings (Daubert hearings) to evaluate expert testimony on causation. Despite the plaintiffs’ efforts, the federal court dismissed the cases in 2024 due to lack of admissible expert evidence linking acetaminophen to autism, though appeals remain pending. This MDL has seen hundreds of plaintiffs actively involved, with thousands more potentially interested but not yet filed in federal court. The litigation’s rapid growth and high-profile nature have drawn national attention, but the dismissal has limited its current impact in federal courts.
Parallel to the acetaminophen litigation, another substantial wave involves baby food autism lawsuits. These lawsuits allege that exposure to toxic substances in baby food products from major brands like Gerber, Beech-Nut, and Sprout caused autism or ADHD in children. This litigation is centralized in a separate MDL in the Northern District of California and has been steadily growing, with over 180 active cases as of mid-2025 and expectations of many more filings. These cases claim strict liability, negligent failure to warn, and defective design, seeking compensatory and punitive damages. Unlike the acetaminophen MDL, baby food lawsuits are still progressing toward discovery and potential trials, with some cases already scheduled for trial in state courts.
The scale of these autism-related lawsuits is notable but still smaller compared to some of the largest mass torts in U.S. history, such as the tobacco litigation, asbestos claims, or opioid lawsuits, which involved tens or hundreds of thousands of plaintiffs and generated multi-billion-dollar settlements. However, the autism class actions are unique in their focus on developmental disorders and alleged prenatal or early childhood exposures, whic
