Restless Legs Syndrome and Related Disorders - Medications

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Side Effects. Common side effects of all these drugs vary but may include feeling faint or dizzy (especially when standing up), headaches, abnormal muscle movements, rapid heartbeat, insomnia, bloating, chest pain, and dry mouth. Nausea may be especially common. Adding the drug domperidone may help to relieve this side effect. Because these drugs may also cause daytime drowsiness, special care should be taken when driving. In rare cases, they can cause hallucinations or lung disease.

Dopaminergic drugs may also have the following side effects, which can be limiting factors in the value of these medications for RLS. (They tend to be more severe with L-dopa than the newer dopamine receptor agonists.)

• Rebound Effect. The rebound effect causes increased leg movements at night or in the morning as the dose wears off.
• Augmentation. Long-term use of these drugs may eventually intensify symptoms of restless legs syndrome in the late afternoon or evening. Symptoms of restlessness, in severe cases, extend to the upper part or the whole body and may occur when walking. About 30% of patients who take the dopamine receptor agonists have reported augmentations symptoms compared to 70% who take L-dopa. As the newer drugs are taken for longer periods and at higher doses, however, their augmentation rates may become closer to those of L-dopa. In general, however, occasional use of any drug poses a very a low risk for augmentation.
• Tolerance (Loss of effectiveness). Long-term use can lead to loss of effectiveness. Adding a drug called entacapone (Comtan) may prolong the duration of action of carbidopa-levodopa therapy (Sinemet), but it can cause nausea.

Using the lowest dose possible can minimize these effects.

Withdrawal Symptoms. Patients who withdraw from these drugs typically experience very severe RLS symptoms for the first two days after stopping. RLS eventually returns to pre-treatment levels after about a week. The longer the drugs have been taken, the worse the withdrawal symptoms.