Hi, Coricidin - is a combination of Chlorphenamine and Dextromethorphan. Chlorphenamine is a first-generation alkylamine antihistamine used in the prevention of the symptoms of allergic conditions such as rhinitis and urticaria. Its sedative effects are relatively weak compared to other first-generation antihistamines. It doesn t have much side effects to mention. Dextromethorphan is a steroid and is an antitussive (cough suppressant) drug. Side-effects of dextromethorphan use can include: At normal doses: Sudden infant death syndrome body rash/itching nausea drowsiness dizziness Closed-eye hallucination Difficulty breathing At dosages 12.5 to 75 times the recommended therapeutic dose: hallucinations disassociation vomiting blurred vision dilated pupils sweating fever bruxia hypertension shallow respiration diarrhea urinary retention Dextromethorphan can also cause other gastrointestinal disturbances. Dextromethorphan had been thought to cause Olney s Lesions when administered intravenously; however, this was later proven inconclusive, due to lack of research on humans. Tests were performed on rats, giving them 50 mg and up every day up to a month. Neurotoxic changes, including vacuolation, have been observed in posterior cingulate and retrosplenial cortices of rats administered other NMDA antagonists such as PCP, but not with dextromethorphan. In some rare documented cases, dextromethorphan has produced psychological dependence in some people who used it recreationally. However, it does not produce physical addiction, according to the WHO Committee on Drug Dependence. So it is not advised to take for long term.