Hydrocodone is an opioid medication for moderate to severe pain. Its brand names are Hysingla and Zohydro ER. This medicine should not be crushed or broken as it may lead to a fatal dose. It also has a high risk of addiction due to its opioid component. The side effects include confusion, severe drowsiness, nausea, weakness, loss of appetite, pain when urinating, constipation, and cold symptoms.