California should not list acetaminophen as a carcinogen. It is a safe, important pain reliever

By Dr. Shalini Shah and Dr. Edward Mariano, Special to CalMatters

Protecting consumer safety is an important part of government oversight, but a regulatory effort currently underway in California could actually pose more harm than good. 

There is debate over whether acetaminophen should be added to the Proposition 65 list, which serves as a warning to the public of cancer-causing chemicals.

That is unnecessary and unwise, and presents the type of regulatory overreach that could make Proposition 65 meaningless. Already people glaze over the ubiquitous Proposition 65 signs in parking garages, office buildings, or other public places that people have to visit. 

Did you know that even Disneyland can cause cancer? California’s Office of Environmental Health Hazard Assessment has acknowledged that there’s a danger to overwarning, and that the label should be preserved for real health risks. 

There are now more than 900 chemicals on the Proposition 65 list. You would be correct to assume that somel lawyers can make a full-time job of Proposition 65 lawsuits and payouts.

Recently, coffee was going to be added to the list, but ultimately received an exemption. Similar to coffee, adding acetaminophen to the list is a step too far.

More than 50 million Americans use an acetaminophen-containing medicine each week to treat pain, fever, and minor aches such as those due to the common cold, headache, backache, minor pain of arthritis, toothache, muscular aches, and menstrual cramps. 

It is an active ingredient in common medications like Tylenol, Midol, Sudafed and Excedrin. It has been in use for decades, and studied extensively in human and animal research. There is no clear evidence that acetaminophen should be considered a carcinogen. Adding it to the Proposition 65 warning list could actually create harm by pushing people toward other medications that are not as safe or effective, or bring much greater risk of side effects including addiction.

As anesthesiologists and pain specialists, we work to ensure our patients have access to appropriate options to control their pain. We work with patients to develop tailored pain management plans which often involve over-the-counter pain medications to reduce reliance on opioids, which can be highly addictive.

Acetaminophen is the best option for certain patient populations. It is the only pain reliever and fever reducer that is safe for infants under 6 months old. It is the most appropriate option for patients who have stomach conditions, heart or kidney disease, high blood pressure, asthma, or who are pregnant.

Most drugs, if misused or given in high doses, can be harmful. But the literature does not support labeling acetaminophen as a carcinogen in humans at regular dosages. Science shows that when used appropriately, the benefits of taking acetaminophen outweigh rare or potential risks.

We encourage the Office of Environmental Health Hazard Assessment to quickly conclude its evaluation, see that the research does not justify alarm, and avoid adding acetaminophen to the list of carcinogens.

This is not a better-safe-than-sorry situation. Evidence does not show a clear cancer risk. Adding a Proposition 65 warning would cause fear and confusion among patients, and push some to more risky medications. That would harm, not help, human health. 


Dr. Shalini Shah is vice chair of the Department of Anesthesiology & Perioperative Care at UC Irvine Health and chair of the Committee of Pain Medicine at the California Society of Anesthesiologists. [email protected] Dr. Edward Mariano is a professor of Anesthesiology, Perioperative and Pain Medicine at Stanford University School of Medicine, [email protected]  They wrote this commentary for CalMatters.

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