Tramadol 37.5/325 mg contains two medications: tramadol 37.5 mg and acetaminophen 325 mg. Tramadol belongs to a class of drugs known as opioid analgesics; on the other hand, Acetaminophen is used to relieve pain. Its mechanism of action is mixed and is indicated for the treatment of severe pain that occurs in adults. This drug has a central type of action that has a bright analgesic effect that works by changing how your brain senses pain. Tramadol tablets are available as immediate-release and extended-release tablets in which extended-release medicines are released into the body slowly, over time. The yellow, capsule/oblong with the imprint “APO” on one side and “37.5-325” on the other has been identified as Tramadol 37.5/325 mg which is supplied by Apotex Corp. The number of doses recommended by a doctor, the time allowed between doses, etc. depend on the medical reason for which you are using the tablet. Some side effects and symptoms that may be caused by Tramadol 37.5/325 mg include feeling irritable, anxious, trouble sleeping, increased blood pressure, fast breathing rate, fast heart rate, yawning, muscle weakness, sweating, nausea, vomiting, a loss of appetite, diarrhea, or stomach cramps.