Dental Dose: The hidden risk of opioids with acetaminophen

Dental Dose is a twice-monthly video series featuring pharmacologist Tom Viola, RPh. In each episode, Viola shares bite-sized pieces of dental pharmacology news, facts, and myths.

Acetaminophen is one of the safest drugs in dentistry. Opioids are among the riskiest. Put them together, and you have an effective pain reliever that comes with one side effect you may not think about. Viola shared what you need to know in the latest episode of Dental Dose.

Acetaminophen is known as being a safe medication for high-risk patients, including babies, pregnant patients, and older adults. Patients will often know it's a good way to reduce fever and pain.

"That's how acetaminophen gets its moniker of the safe analgesic," Viola said. "And it is very safe. But up to a certain dose."

The U.S. Food and Drug Administration (FDA) recommends taking no more than 4,000 mg of acetaminophen in a 24-hour period. That's because excess acetaminophen can build up in the liver, and when it's broken down, can cause liver damage.

However, certain factors, like drinking alcohol, can affect how the body processes acetaminophen. In some cases, acetaminophen can build up in the liver even if a patient stays under the 4,000-mg limit.

That is a risk to consider when dentists prescribe patients an opioid that contains acetaminophen, Viola said.

"If your patient is taking a high enough dose of let's say Vicodin or Norco, where the opioid component is causing respiratory depression, I'd almost guarantee at that point that the acetaminophen dose is also so high that it's causing liver damage at the same time," he said.

Despite the risks of opioids on their own and in combination with acetaminophen, they still have their place in dentistry, Viola said. He advised only prescribing opioids to treat severe pain that can't be relieved by a combination of ibuprofen and acetaminophen.

"The smallest amount necessary, the smallest dosage," Viola said. "The smallest number of tablets for the shortest period of time."

Learn more about the side effects of opioids and acetaminophen in the video below. Also, be sure to check out this list of evidence-based substance abuse screening tools mentioned by Viola in the episode.