Dextromethorphan: Adverse Reactions The drug hardly causes typical opioid side effects. High and very high doses in particular can cause neuropsychiatric symptoms (euphoria, restlessness, misperception, hallucination, "schizophrenic" reactions) that are similar to the effects of the hallucinogenic agent phencyclidine. It has not been established whether these problems are related to the metabolic phenotype of the individuals. Besides that, there are gastrointestinal symptoms and skin reactions. The most immediate risk arising from dextromethorphan seems to be its sporadic abuse. A few cases of addiction have been recorded. Dextromethorphan: Interactions In combination with monoamine oxydase inhibitors dextromethorphan can cause a severe reaction ("serotogenic syndrome" with fever, hypertension, arrhythmias): avoid this combination if possible! Copyright © 1996 Infomed-Verlags AG