A mother whose 4-month-old son died after taking over-the-counter cough and cold medicines sued two distributors of the drugs, saying they should have known the dangers of a key ingredient and warned consumers.

The lawsuit filed Wednesday is one of the first since Federal Drug Administration hearings last month where health experts testified that parents should not give children younger than 6 such medicines because they don't work and can be harmful.

Dimitria Alvarez of Bloomington in central Illinois found her son dead in his crib Oct. 8, 2001, four days after he had begun sniffling and coughing with an apparent cold.

Alvarez gave her son McNeil-PPC Inc.'s Infant Tylenol Cold Decongestant Plus Cough and Walgreen-brand Pediatric Drops-Cough Plus Cold, according to the lawsuit. Both contain dextromethorphan.

A coroner's report says Devon Mehlberg-Alvarez died of dextromethorphan intoxication, with tests showing his system metabolized the ingredient slowly, allowing it to build up to toxic levels, according to the lawsuit.

"She's the one who found the child dead," said Alvarez's attorney, Ralph Davis. "You can only imagine what one goes through."

The 41-page lawsuit was filed in Lake County Circuit Court and seeks unspecified damages. It names Deerfield-based Walgreen Co. and McNeil, a unit of New Brunswick, N.J.-based Johnson & Johnson, claiming the companies knew the hazards of dextromethorphan for years but failed to warn consumers.

Walgreen spokeswoman Carol Hively said Wednesday that company lawyers had seen the lawsuit and suggested the boy might have been given the cold medicines at the same time.

"The Food and Drug Administration has found that these products are safe when used as directed," she said. "But they should not be combined with other products with the same active ingredient."

Davis denied that possibility, saying the baby got the medicines sequentially and in the indicated doses over the course of several days.

Hively also said Walgreen labels complied with FDA regulations, adding "we were among the first retailers to voluntarily recall these products last month out of an abundance of caution."

A spokesman for McNeil, which also voluntarily recalled its products, declined to comment.

Drug makers preemptively pulled cold medicines targeted for babies and toddlers off the market Oct. 11, a week ahead of the FDA hearings and after the administration reported deaths linked to the remedies in recent years, primarily from unintentional overdoses.

The boy's mother had earlier believed the baby's metabolic rate led to his death, but concluded after the FDA hearings that the medicines were to blame, the lawsuit said.