Drug tolerance to opioids and other narcotics can develop with long use. This means that higher doses will be needed to keep the same effect. It also means that the body will eventually learn to operate normally with that amount of medication. When the user tries to stop taking these pain killers, withdrawal symptoms appear. Withdrawal from opioids is not life-threatening, but it can be uncomfortable, so it is important to get medical supervision. These symptoms include restlessness, pain in the bones and muscles, insomnia, diarrhoea, vomiting and involuntary leg movements. However, the psychological symptoms, including cravings, depression, anxiety, and insomnia, are more likely to lead a person to relapse if they are not working with a doctor to safely detox.