WASHINGTON D.C. After hundreds of deaths overseas from contaminated cough syrups, the U.S. Food and Drug Administration (FDA) has cracked down on lax testing practices by dozens of makers of their healthcare products.

This year, the FDA has warned at least 28 companies, including U.S.-based companies and exporters from India, South Korea, Switzerland, Canada, and Egypt, for failing to prove sufficient testing of ingredients used in over-the-counter drugs and consumer products for the toxins, ethylene glycol (EG) and diethylene glycol (DEG).

In 2023, it warned more manufacturers for failing to test raw materials susceptible to EG and DEG contamination than in the five years combined.

In an interview with Reuters, the FDA said it has not found evidence that products contaminated with DEG and EG have entered the U.S. supply chain, and the number of warning letters issued in a given period "is not a comprehensive marker of our oversight."

To identify contamination more effectively, the agency now requires manufacturers to check individual containers of ingredients rather than just sampling raw materials, stated Peter Lindsay, a lawyer at Paul Hastings in Washington, D.C., specializing in FDA regulation and compliance.

"They are upping the bar a little bit and trying to get the industry to understand and recognize some of the risks in these areas," he said.

Cough syrups made in India and Indonesia, which contained high levels of DEG and EG that could cause acute kidney damage and death, have been linked to the deaths of more than 300 children worldwide.

The deaths caused by poisoning have led to criminal probes, lawsuits and greater regulatory scrutiny in many countries.

Earlier this month, Reuters reported that some Indian drugmakers involved in the deaths could not prove that they had purchased pharmaceutical-grade ingredients or tested their medicines for DEG and EG.