Drug Profile

Dextromethorphan is an over-the-counter drug that is sold alone and in combination with other products as a cough suppressant for children and adults. We have previously recommended dextromethorphan as a safe and effective cough suppressant for both children and adults. However, the weight of the evidence now suggests that dextromethorphan is no more effective than an inactive placebo syrup in suppressing a nighttime cough in children.

The study tipping the balance for us to a Do Not Use classification for this drug was published in the July 2004 issue of the journal Pediatrics and was conducted by researchers from the Pennsylvania State College of Medicine, Hershey, Pennsylvania.[1]

Sleep quality for children with coughs was used as the measure of effectiveness to compare over-the-counter cough medication dextromethorphan to placebo. The study involved 100 children with coughs and used a five-question questionnaire to assess sleep quality in both children and their parents. The median age of the children was 4.5 years and their ages ranged from 2.0 years to 16.5 years. To be eligible to participate in the study, the children had to have an acute cough as a result of an upper respiratory tract infection.

No medication was given the first night and the second night patients received either dextromethorphan or a placebo. After both nights, parents were asked to assess the frequency and severity of the nighttime cough and the degree to which it was bothersome.

The study concluded that dextromethorphan was not superior to the placebo in providing nighttime symptomatic relief for children with a cough and sleep difficulty. In addition, the use of this medication did not result in improved sleep quality for the children’s parents. In other words, the drug had no effect on the natural course of cough improvement in children with upper respiratory infection over a 24-hour period.

Older research on the value of these drugs as cough suppressants was conflicting. A type of statistical summary of multiple studies known as a meta-analysis published in the February 9, 2002, British Medical Journal concluded, for adults, that “Over-the-counter cough medicines for acute cough cannot be recommended because there is no good evidence for their effectiveness.”[2]

The American Academy of Pediatrics’ Committee on Drugs has not supported the use of dextromethorphan primarily because there is a lack of proven benefit and some potential for toxicity and overdose.

Even ineffective drugs have the potential to cause adverse effects. In usual doses, dextromethorphan has been associated with loss of muscle tone, severe allergic reactions, and blisters that occur due to the proliferation of a type of cell involved in allergic reactions.

In 2005 the FDA issued a public advisory warning about the abuse of dextromethorphan. This warning came after there were 5 reported deaths of teenagers that were associated with the consumption of powdered dextromethorphan sold in capsules. Dextromethorphan is generally safe at recommended doses, but abuse can lead to death or serious adverse effects such as psychosis, mania, hallucinations, seizures, loss of consciousness, brain damage and arrhythmias.

A series of cases in the Journal of Forensic Sciences in September 2012 reviewed the instances of dextromethorphan abuse that led to assault, suicide or homicide. The concentration of dextromethorphan consumed was above therapeutic dosage. As in these case reports, abuse of excessive dextromethorphan can lead to psychosis and related behaviors.[3]

The Netherlands Pharmacovigilance Center has reported 9 cases of neuropsychiatric adverse drug reactions associated with the use of dextromethorphan. The World Health Organization database contained 17 reports of anxiety, three reports of delusions and 37 reports of hallucinations associated with the use of this drug.[4]

Parents and health professionals have a strong urge to “do something” to ease symptoms in children, even in a mild, self-limiting illness like an upper respiratory tract infection. The lesson from this study is that it is sometimes better to do nothing because the medications have no therapeutic benefit but do carry a known risk of potentially serious adverse reactions.