Story at a glance

  • Acetaminophen, the main ingredient in Tylenol, is a popular painkiller used globally.
  • California legislation will hold a hearing in spring 2020 to determine if it can cause cancer.
  • Studies don’t point to obvious links between acetaminophen and cancer, but note overdosing can cause liver damage.

In California state legislature, a new battle is taking shape over whether or not a popular painkiller, acetaminophen, will be labeled as a carcinogen, according to an AP report. It is the main ingredient in Tylenol.

Global customers know acetaminophen as paracetamol and use it to treat aches, pain and fever. Acetaminophen has been widely available as an over-the-counter painkiller since 1955 and causes limited side effects when used properly, per WebMD

Now state regulators have reviewed a reported 133 studies about acetaminophen, some of which reported various types of cancers as risks of taking the drug. 

While high doses of acetaminophen have been linked to liver damage in other studies, this review concluded that “acetaminophen has been difficult to examine because it is hard to isolate it from other variables that could contribute to cancer, such as smoking.”

Evidence of acetaminophen as a carcinogen was not strong enough for it to be added to the list of accepted as a ‘possible carcinogen’ for the International Agency for Research on Cancer after reviewing it in both 1990 and 1999.

The U.S. Food and Drug Administration acknowledged the liver damage can be a potential side effect, but noted that labeling the painkiller as a carcinogen would be “false and misleading,” as well as illegal. 

According to California law, Proposition 65, or the Safe Drinking Water and Toxic Enforcement Act of 1986, requires the state “maintain and update a list of chemicals known to the state to cause cancer or reproductive toxicity.”

Ultimately, a panel of scientists appointed by the governor of California can add acetaminophen to the list. A public hearing on the chemical’s classification has been scheduled for the spring of 2020.  


Published on Jan 21, 2020