New research suggests that pregnant women who use acetaminophen, which is the active ingredient in the popular painkiller Tylenol, may increase their risk of giving birth to a child with attention deficit hyperactivity disorder (ADHD).
An international group of researchers published a study in the medical journal JAMA Pediatrics on February 24, which appears to show an association between the Tylenol and ADHD, as well as hyperkinetic disorders (HKDs). More than half of pregnant women use acetaminophen, meaning the findings could have widescale implications.
Researchers studied 64,322 children and mothers enrolled in the Danish National Birth Cohort from 1996 to 2002, looking at parental reports of behavioral problems, HKD diagnoses from Danish health care sources and ADHD drug prescriptions.
The findings suggest that mothers who used acetaminophen were 29% more likely to give birth to a child who would eventually be diagnosed with ADHD, and 37% more likely to give birth to a child with HKD by the age of seven.
“Maternal acetaminophen use during pregnancy is associated with a higher risk of HKDs and ADHD-like behaviors in children,” the researchers concluded. “Because the exposure and outcome are frequent, these results are of public health relevance but further investigations are needed.”
An editorial published in the same issue warned against jumping to conclusions from the study. Researchers from the Cardiff School of Medicine indicate that it may be too early to say that acetaminophen is causally linked to ADHD.
“[A]lthough the findings are potentially important, caution should be exercised in ascribing causation to statistical associations between prenatal risk factors and adverse outcomes,” the editorial states. “Although an exposure-response relationship is reported for all 3 outcomes, with increasing frequency of acetaminophen use (indexed by number of weeks of exposure) reported as showing stronger associations, the interpretation of this relationship is not straightforward.”
Acetaminophen Liver Damage
The findings come as Johnson & Johnson faces more than 120 Tylenol liver damage lawsuits filed in the federal court system on behalf of former users, which allege that the drug maker failed to adequately warn about the risks associated with using the common pain medication.
All of the complaints raise similar allegations that Johnson & Johnson built an image for their blockbuster medication as safe and effective by withholding important information about the link between Tylenol and liver problems.
Amid the mounting lawsuits, the U.S. Judicial Panel on Multidistrict Litigation consolidated all cases filed in U.S. District Courts throughout the country in April 2013. The cases are centralized before U.S. District Judge Lawrence F. Stengel in the Eastern District of Pennsylvania for coordinated discovery and pretrial proceedings.
Tylenol is one of the most widely used painkiller medications in the United States, which has been used by millions of Americans. The medication contains acetaminophen as the active pharmceutical ingredient, which has been identified in recent years as a leading cause for liver injury in the United States.
The FDA has indicated that acetaminophen may be responsible for more than 50,000 emergency room visits each year, including 25,000 hospitalizations and over 450 deaths annually. In recent years, efforts have been ramped up to bring the risk of acetaminophen overdose to the public’s attention and to reduce the amount of liver injury cases linked to the popular analgesic, which is also found in other pain killers and a number of cold medications.
In 2011, Johnson & Johnson lowered the maximum recommended dosage on Tylenol and other acetaminophen-based products from 4,000 mg per day to 3,000 mg per day. However, the lawsuits allege that the drug maker has withheld important safety information from the public for decades, ignoring the narrow window between the recommended dosage for Extra Strength Tylenol and the risk of liver injury.