Dextromethorphan is a common ingredient in many cough syrups and cough suppressant medications. Dextromethorphan works by inhibiting the nerves involved in the cough reflex, which lessens the urge to cough. Despite its presence in over-the-counter medications, there are a number of risks associated with dextromethorphan use, including dangerous drug interactions and the possibility of overdose or abuse.
Side Effects
Consumption of products containing dextromethorphan can cause a number of different side effects, PubMed Health explains. Some of these side effects are a result of the gastrointestinal system being disrupted. This can result in patients experiencing stomach pain, nausea and vomiting. Dextromethorphan also has a number of effects on the brain aside from cough suppression. Patients may experience restlessness or nervousness when taking dextromethorphan. In addition, dextromethorphan can cause patients to become dizzy, drowsy or light headed. Consequently, it is important for patients taking dextromethorphan to avoid driving, operating heavy machinery or participating in activities that require high levels of alertness.
Sedative Potentiation
Dextromethorphan can also be dangerous because of its ability to interact with other medications. For example, dextromethorphan is able to potentiate the effects of other medications which depress the central nervous system, including alcohol, narcotics, tranquilizers, sedatives/hypnotics and certain types of antidepressants. As a result, patients who take dextromethorphan and these medications may become extremely drowsy. Dose adjustments are commonly needed when taking these medications with dextromethorphan. For example, barbiturate dosage should be cut in half, RxList explains, and narcotic dosing should be reduced by between 25 and 50 percent.
Dextromethorphan and Monoamine Oxidase Inhibitors
Dextromethorphan should not be taken with a class of medications known as monoamine oxidase inhibitors, also known as MAOIs. MAOIs are a class of antidepressant medication that includes isoniazid, hydralazine, selegiline and linezolid. These medications work by preventing the breakdown of certain chemicals in the brain. Patients taking dextromethorphan along with MAOI drugs may develop a sudden drop in blood pressure as well as an extremely high fever. This drug interaction can be fatal.
Overdose/Abuse
When dextromethorphan is taken in high doses, either accidentally or for illicit purposes it can cause a number of different effects, the United States Drug Enforcement Agency explains. There are four main stages of dextromethorphan intoxication depending on the dose taken. Between 100 and 200 mg of dextromethorphan can cause mild stimulation. The second stage, achieved by taking between 200 and 400 mg of the drug can result in hallucinations and euphoria. 300 to 600 mg can cause distortions in visual perception and loss of motor control. Finally, doses between 500 to 1500 mg may result in dissociative sedation, which is a trance-like state commonly seen with some anesthetics.
