April 17, 2012 -- A Colorado girl is dead after taking a lethal combination of two common cold and allergy medicines, and Colorado authorities are investigating her grandmother, who was looking after the tiny 5-year-old.
Kimber Michelle Brown was spending the night with her 59-year-old grandmother, Linda Sheets, at the time of her death on Feb. 12. Sheets was reportedly treating the girl for flu-like symptoms.
The coroner's report, which came out this week, ruled the overdose was accidental, caused by dextromethorphan, an ingredient commonly used in cough syrup. Kimber's blood levels were two and a half times higher than the recommended dosage.
She also had higher than therapeutic levels of cetirizine, which is the main ingredient in the allergy medicine Zyrtec.
Kimber's parents, Raelyn Anderson-Brown and Mike Brown, live in Durango, Colo., which is about nine miles from Hermosa, where she died.
Investigators say Sheets, who is Anderson-Brown's mother, may not have measured the medicine properly, or the child may have also taken some herself.
Now, the Sixth Judicial District Attorney's Office is investigating whether criminal charges will be filed, according to the Durango Herald, although police have said so far there is no evidence of wrongdoing.
"I consider it a certified combination of drugs, with the dextromethorphan being the highest level," La Plata County Coroner Dr. Carol Huser told ABCNews.com.
Combining the two depressants produced a greater toxicity than each drug would have caused alone, she said.
Blood levels were taken several hours after the child's death. Those were the only drugs in the girl's system, except for some that the medic administered "to try to save her," said Huser.
The toxicology report showed that the little girl, who weighed only 46 pounds, had 96 nanograms per millilitre of dextromethorphan in her blood. The upper limit for this drug in adults is 40 ng/ml.
Kimber also had 490 ng/ml of cetirizine in her system. A normal dosage would be between 271 and 352 ng/ml.
Huser said he had never seen a death from these medications before, but warned about the dangers of over-the-counter medicines.
"As a society in general, we are way too dependent on drugs -- we take them as knee-jerk reaction and it's not wise," she said.
As for the criminal charges against the family, Huser said, "I can't speak for the state attorney general, but it's highly unlikely."
"I have no reason to suspect any ill intent," Huser wrote in the toxicology report. "The degree of negligence in either measuring an inappropriate dose or leaving medications within reach of a child does not, in my view, rise to the level I require for a certification of homicide."
Death from Cough Medicine is Rare
Dr. Douglas Carlson, an emergency room pediatrician at St. Louis Children's Hospital and Washington University School of Medicine, said the coroner's report makes sense.
"While death is an unusual side effect of dextromethorphan, it is known to occur," said Carlson, who did not treat Kimber. "The efficacy of over-the-counter cough medications is minimal in children, so we recommend not using them in less than 2 years and be careful with those under age 6."
According to the coroner's report, Kimber complained of leg pain, cramps and muscle spasms hours before her death. Huser said that was consistent with drug toxicity as her body began to shut down.
Carlson said those symptoms were inconsistent with dextromethorphan, which causes "drowsiness and fatigue."
An overdose of dextromethorphan usually triggers changes in the child's mental status leading to "irritability and confusion," according to Carlson. "That's why teens use it to get high -- for the sensory perceptions."
The drug in higher doses can cause cardiac abnormalities and arrhythmias that can cause the heart to stop functioning, he said.
"Dextromethorphan is the most common ingredient in the country," said Carlson. "When you use it with small children, make sure to follow the label directions and measuring device with the bottle."
"I am not aware of fatal reactions when used alone," he said.
As cetirizine, found in the allergy medicine Zyrtec, Carlson said the package warns that when used with dextromethorphan, the combination can depress the central nervous system or lead to psychomotor impairment.
That drug could have explained the cramping and twitching, according to Dr. John Spangler, an associate professor of family and community medicine at Wake Forest University School of Medicine.
"Instead of sedation, which can occur with antihistamines, some children have a paradoxical reaction," he said.
But, warned Dr. Donna Seger, medical director of the Middle Tennessee Poison Center, there could have been other issues at play, such as a viral or other infection.
"Had she seen a physician?" she asked.
"We shouldn't cause a scare about these drugs unless we have evidence that they caused a problem," said Seger. "A lot of children take these drugs."
ABC's Dr. Christopher A. Tokin contributed to this story.