Syndol tablets are used to treat mild to moderate pain they are recommended for the symptomatic relief of headaches it can also be used to treat migraine rheumatic pain period pain toothache and neuralgia syndol contains three strong painkilling ingredients these are codeine an opioid painkiller codeine works by mimicking actions of pain relieving chemicals called endorphins thus blocking the transmission of pain signals paracetamol this painkilling medicine is thought to work