Opioid addiction is becoming a global problem and is currently the primary cause of drug overdose in the U.S. Opioids such as morphine and codeine are synthetic drugs that cause the same effect as opium. They act on the nervous system to reduce pain and come in the form of capsules, tablets or liquid. Using and abusing opioids can lead to physical dependence along with opioid withdrawal symptoms. Other common opioids include fentanyl, hydrocodone as well as heroin.