Some side effects associated with taking propoxyphene and acetaminophen 100/650 milligram tablets include dizziness, blurred vision, lightheadedness, headache and dry mouth, according to RXList. Other side effects include drowsiness, constipation, upset stomach, nausea and vomiting, and sedation.
Some serious side effects when taking propoxyphene and acetaminophen indicate a serious medical emergency requiring evaluation by a medical professional, notes RXList. Signs of a potential allergic reaction include difficulty breathing, hives, and swelling of the tongue, lips, throat or face.
Doctors prescribe the combination of propoxyphene and acetaminophen to treat mild-to-moderate pain, reports RXList.. Formerly sold under the brand name Darvocet, propoxyphene and acetaminophen may be available in the United States in generic formulas.