Oxycodone 20 mg is a relief for severe pain.This may be habit- forming. It may cause serious breathing problems. It is caused by drinking alcohol or using street drugs. Its symptoms are slowed breathing,long pauses between breaths and shortness of breath. It works by changing the brain and nervous system. Its side effects are nausea,vomiting,headache,weakness and tiredness. May it be an overdose ,if you had depression or another mental illness. It signals pain between the brain and body. It comes in different dosages like; tablets, capsules and liquid.