Because this drug contains an antihistamine and decongestant, it has several potential side effects. The decongestant in chlorpheniramine maleate can cause a rapid heart rate, increased blood pressure, a drop in blood pressure upon standing, palpitations, dry nose and throat and a sore throat. Other potential side effects include blurred vision, double vision, tinnitus, fatigue, headache, confusion, loss of coordination, dizziness, euphoria, drowsiness, constipation, dry mouth, diarrhea, difficulty urinating, increased appetite, chest tightness, respiratory depression and wheezing.