The Food and Drug Administration has endorsed the use of a safety device for bottles of children’s medication containing liquid acetaminophen, the active ingredient in Tylenol.

Called a flow restrictor, the device fits into the top of a bottle to prevent kids from inadvertently squeezing or sucking out too much liquid. In high doses, acetaminophen can result in liver damage and even death.

While the FDA guidance released earlier this month does not require use of the devices, it is a strong signal to manufacturers that flow restrictors are considered an important safety feature to help reduce accidental overdoses.

“This is definitely significant,” said Dr. Dan Budnitz, a scientist for the Centers for Disease Control and Prevention who is leading an effort to make children’s medicine safer.

The move comes 20 months after ProPublica and Consumer Reports reported on the devices, whichhave been shown to greatly reduce the liquid dose that children can accidentally remove from a bottle. About 10,000 children each year visit the emergency room for overdosing on liquid medicines, many of them containing acetaminophen, studies show.

The ProPublica story uncovered internal FDA documents showing that agency scientists had been urging the adoption of such devices since at least 2001. But FDA officials hesitated, debating whether the agency had the power to require their use.

In a statement, the agency said drug manufacturers would “benefit from the guidance’s clear advice on the formulation, labeling, and delivery of these products.”

In 2011, a panel of FDA outside advisors was scheduled to discuss the use of flow restrictors, among other measures. While not binding, the recommendations of such advisors are typically adopted by the FDA.

A month before the meeting, pharmaceutical industry representatives announced that they would voluntarily begin adding flow restrictors to infants’ and children’s pediatric medicine bottles. McNeil Consumer Healthcare, the Johnson and Johnson unit that makes Tylenol, led the way.

The flow restrictors would help “reduce the incidence and magnitude of accidental acetaminophen exposures,” Dr. Edwin Kuffner, a McNeil executive, said in a letter to health care professionals. The company had first used a type of flow restrictor on Infants’ Tylenol in 1999.

The FDA left the design of the flow restrictors to the industry. Several companies manufacture devices with different designs, costing from 2 cents to 10 cents apiece.

Consumer Reports’ tested the devices on the market. While all helped reduce the chance that kids would drink too much medicine, some devices worked better than others. McNeil, which has long promoted the safety of its Tylenol products, was using one of the less effective types of flow restrictors, the test showed. Family Dollar, a discount store, had a store brand with one of the more effective types.

After the articles, Budnitz, Consumer Reports, government regulators and industry representatives such as McNeil began working together to develop standards to test the efficacy of flow restrictors. Final results are expected to be issued in 2016 by ASTM International, a group that sets guidelines for more than 12,000 products and services.

The FDA’s formal guidance has the effect of pushing makers to use flow restrictors on acetaminophen products for kids. And the standards will provide makers with a uniform way to gauge the performance of the devices.

“It stands to reason that flow restrictors may be used as an effective safeguard against unintentional harm from oral liquid [over-the-counter] products, such as acetaminophen,” the FDA said.

Still, neither the drug agency nor industry has indicated a willingness to require the flow restrictors for other liquid children’s medicines, such as prescription cough medicine. Researchers believe that installing the devices in all kids’ liquid medicines might help further reduce accidental overdose.

“It’s incremental progress, but it definitely is progress,” Budnitz said.

In a statement, McNeil said that it believes the “first line of defense” against accidental overdose is for parents and caregivers to store medicine in a high, out-of-sight place after use. The company said it had not changed the type of flow restrictor that it uses.

“We believe flow restrictors help prevent accidental and unsupervised ingestions and accordingly have elected not to change the approach,” the company said.

The Consumer Healthcare Products Association, an industry group for over-the-counter medicine companies, said its members welcomed the measure.

“We are pleased to see [the] FDA finalize this guidance,” the association said in a statement.