Fentanyl use disorders can begin with dependency and develop into an addiction. Common signs of fentanyl addiction are usually associated with changes in behavior. There may be signs and symptoms of fentanyl side effects, such as nausea, drowsiness, or elation.   If fentanyl withdrawal symptoms develop, they will have difficulty in sleeping, managing their physical pain, and keeping food down. Fentanyl addiction also presents neurotic and erratic behaviors. A common side effect of fentanyl use…