According to WebMD, Tussionex is a drug prescribed for symptoms of colds and allergies, including coughing, watery eyes, itchy eyes, nose and throat, runny nose and sneezing. It is a combination of hydrocodone and chlorpheniramine.
WebMD explains that, because Tussionex contains a narcotic, there is a possibility of withdrawal symptoms if taken too long or at high doses. Some patients experience nausea, vomiting, diarrhea, restlessness and sweating. To avoid problems, the dosage is often cut back slowly.
Common mild or moderate side effects include fatigue, drowsiness, nausea, blurred vision and dry mouth, indicates WebMD. More serious side effects, such as mood changes, abnormal heartbeat, seizures or difficulty breathing, should be reported to a doctor.