The Hidden Risk in Your Medicine Cabinet

More than 1,000 medications are potentially toxic to the liver. But one drug stands out as the leading cause of acute liver injury in the United States, and it’s likely sitting in your medicine cabinet.

That drug is acetaminophen, an active ingredient in more than 600 over-the-counter and prescription medications.

“Roughly 30 to 50 percent of hospitalizations from acetaminophen result from unintentional overdoses,” said Jeffrey Yin, PharmD, a clinical pharmacist at UC San Diego Health who specializes in liver disease.

Why Acetaminophen Is So Risky

The real problem is acetaminophen’s ubiquity. It’s found in medications for cold, flu, allergies, sleep, headaches, arthritis and pain. According to the American Liver Foundation, it’s the most common drug ingredient in the U.S.

“Because it’s embedded in so many products, people can easily double up without realizing it,” Yin said. “It’s especially easy to overdose with liquid medications, where dosing errors or taking a casual swig can push someone over the safe limit.”

How Much Is Too Much?

For adults without chronic liver disease who don’t regularly consume three or more alcoholic drinks a day, the recommended dose of acetaminophen is 650 to 1,000 mg every four to six hours, not to exceed 3,000 mg per day.

Just how easy is it to cross that threshold? One extra-strength painkiller and fever reducer contains 500 mg of acetaminophen. If you take two tablets three times a day, you're already at the max dose. Add in a cold or allergy medication containing acetaminophen, and you could be putting your liver at risk. (Read more about drug-induced liver injuries.)

Tips to Protect Your Liver

Yin advises tracking how much acetaminophen you consume across all medications. Look at the labels and tally the total daily amount. Stay under the 3,000-mg limit.

Some tips:

• Skip combination products. If you don’t need every ingredient and your only symptom is a runny nose, choose a product that treats just that, not one that also includes a fever reducer.
• Avoid unnecessary use. “I have patients who take Tylenol PM for sleep, even if they have no pain. They’re getting acetaminophen with no therapeutic benefit,” Yin said. “Instead, choose an acetaminophen-free sleep aid.”
• Be mindful with alcohol. Even moderate chronic alcohol consumption increases your risk for acetaminophen toxicity.
• When possible, try non-drug methods. For fevers, you can try hydration, rest, or cool compresses to ease symptoms.

Other Liver-Stressing Substances

Acetaminophen isn’t the only concern. Yin also cautions against overuse of other drugs and supplements known to affect the liver, including:

• Certain antibiotics, such as rifampin (used to treat tuberculosis)
• Psychedelic mushrooms, like psilocybin
• Herbal remedies, especially St. John’s wort and kava kava

Why Herbal and Dietary Supplements Could Have Potential Risks

While plants offer therapeutic benefits, they can also be unpredictable and potent.

Herbal and dietary supplements are minimally regulated in the U.S. Manufacturers aren’t required to prove safety or effectiveness. Prescription medications, in contrast, are carefully dosed and tested for safety.

Yin emphasizes that liver injuries linked to supplements have tripled in recent years. A 2019 study found that more than half of the products taken by patients with liver injury either had hidden ingredients or were missing listed ingredients.

“Even when herbals and dietary supplements accurately reflect what is on their label, these products cannot be assumed to be safe just because they are purported to be natural,” Yin said.