Narcotic drugs like fentanyl have not been reported to cause restless leg syndrome. In fact, narcotic drugs are sometimes used to treat the disorder.

Fentanyl is a synthetic narcotic drug that is 50 to 100 times as strong as morphine. Fentanyl has traditionally been administered as part of the anesthetic in people undergoing surgery. It is also routinely used to treat postoperative pain just after surgery. In recent years fentanyl has been used to treat severe pain due to cancer and other diseases. Fentanyl is usually administered using a "patch" that delivers the drug through the skin.

Like all narcotic drugs, fentanyl has the potential to cause withdrawal symptoms when discontinued. The signs of withdrawal can include anxiety, irritability, drug craving, rapid breathing, yawning, runny nose, gooseflesh, nasal stuffiness, muscle aches, abdominal pain and cramping, sweating, confusion and tremors. Withdrawal symptoms can be seen in the first 24 to 48 hours after discontinuing use of fentanyl patches.

Restless legs syndrome (RLS) is a relatively common neurological disorder that is seen in up to 15 percent of people. The incidence of RLS increases with age, and is higher in women than in men. RLS can run in families, especially in people who develop the symptoms before 40 years of age.

The main symptom is a distressing, irresistible urge to move the legs. Many people with RLS complain of a "creepy-crawly" sensation deep in the legs as well. The symptoms are brought on with rest (sitting or lying down). Interestingly, the more comfortable a person is, the more likely it is that the symptoms will occur. The reverse is also true. Sitting or lying down in an uncomfortable position reduces the likelihood of having symptoms. The cause of RLS is not known.

Movement relieves the symptoms. Many people with RLS find walking provides almost immediate relief. The relief may only last as long as the person continues to walk, however. Symptoms usually first appear at bedtime or during the night. As the syndrome progresses, symptoms start to occur earlier in the day and become more intense at night. Even when they occur throughout the day, the symptoms become more intense in the evening or at night.