Is Cough Syrup Hallucinogenic? Medicine Influenced Man To Kill Wife, Toxicologist Says

After a North Carolina man who was arrested and charged with murder in the Sept. 1 fatal stabbing of his wife blamed cough syrup for the making him commit the alleged crime, a toxicologist suggested Thursday that the cold medicine consumed by the accused can indeed cause hallucinations similar to those caused by the street drug PCP (Phencyclidine).

Matthew Phelps told authorities at the time of the murder that he did not have any memory of committing the crime as he had taken too much of a cough medicine. He said he might have killed his wife in his sleep. However, Dr. Richard Stripp, a New York-based forensic toxicologist Thursday told People that the cold medicine Coricidin taken by Phelps contained both dextromethorphan and chlorpheniramine. When the syrup is consumed recreationally in quantities greater than prescribed, it can cause euphoria, agitation, psychoses, and dissociative phenomena.

“I’ve seen cases where these drugs have been abused, over the counter, and there have been issues, but I’ve never seen a case like this where someone commits murder under the influence of the drug,” he added.

The National Institute on Drug Abuse (NIDA) also lists Dextromethorphan as one of the two commonly abused cough and cold medicines, the other being Promethazine-codeine cough syrup. When consumed in higher quantities or when no symptoms of a cough and cold are present, they may affect the brain in ways very similar to illegal drugs.

“Dextromethorphan is a dissociative anesthetic that is designed to be an anesthetic and can cause out of body experiences and one can lose their ability to sense pain,” Stripp said. “Chlorpheniramine is a cough suppressant and that particular drug is abused, and the reason it is abused is if you take high levels of it, the drug’s properties are similar to PCP.”

According to NIDA, users of high doses of dextromethorphan described effects in the range of mild stimulation or intoxication and at high dosages sensations of physical distortion and hallucinations. The comparison to PCP or “angel dust,” is also valid as similar symptoms including delusions and erratic behavior are reported by those who abuse it.

A statement available on the website of Crocidin — the syrup Phelps took — describes the abuse of over-the-counter products including those that contain dextromethorphan as a "long-standing issue" and says the cough suppressant is safe when used as directed.

In Phelps’ case, being under the influence of a cough and cold medicine may be a good defense in the court, People reported. This could help Phelps with a lesser charge or, in very rare cases, a not guilty verdict as it could be argued that Phelps was unconscious during the alleged crime and was not able to control his physical actions.

At the time of the incident Bayer, the pharma company that manufactured Crocidin issued a statement saying: "Patient safety is our top priority, and we continually monitor adverse events regarding all of our products. There is no evidence to suggest that Coricidin is associated with violent behavior."