Dopamine Precursors and Agonists for Restless Legs Syndrome

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Dopamine Precursors and Agonists for Restless Legs Syndrome


Dopamine precursors

Generic NameBrand Name
levodopa/carbidopaParcopa, Sinemet

Dopamine agonists

Generic NameBrand Name

How It Works

Dopamine precursors are drugs that the brain converts to dopamine, a chemical (neurotransmitter) involved in controlling movement. Dopamine is involved in movement, sleep, emotions, alertness, and addictive behavior.

Dopamine agonists directly stimulate nerves in the brain that are not naturally being stimulated by dopamine.

Why It Is Used

These medicines are generally prescribed to treat Parkinson's disease. But there seems to be a relationship between restless legs syndrome and abnormalities in how the body produces or uses dopamine. A doctor may prescribe medicine as treatment for continuous symptoms that frequently disturb sleep, in which case dopamine agonists are usually the first choice.

How Well It Works

Levodopa and dopamine agonists have helped many people control symptoms and sleep better.1 For some people, these medicines seem to help at first. But later they seem to make symptoms worse by a process called augmentation. Because this undesired outcome is most associated with regular use of levodopa, most patients who require daily medicine will need a dopamine agonist.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.


Call your doctor if you have:

  • Hives.
  • Agitation or anxiety.
  • Confusion, hallucinations, abnormal thinking, or holding false beliefs that cannot be changed by fact.
  • Clumsiness or unsteadiness.
  • Dizziness, lightheadedness, or fainting.
  • Difficulty swallowing or excessive mouth-watering.
  • Nausea or vomiting.
  • Uncontrollable movements, such as twitching or repetitive movements of the tongue, lips, face, arms, or legs.
  • Unusual tiredness or weakness.
  • Worse tremor.

Common side effects of this medicine include:

  • Belly pain.
  • Dry mouth.
  • Loss of appetite.
  • Nightmares.
  • Passing gas.

Dopamine agonists

Call your doctor right away if you have:

  • Hives.
  • Dizziness, lightheadedness, or fainting.
  • Confusion or hallucinations.
  • Nausea.
  • Sudden attacks of sleepiness where you fall asleep without warning, even in the middle of the day.
  • Uncontrollable movements, such as twitching or repetitive movements of the tongue, lips, face, arms, or legs.
  • Unusual tiredness or weakness.

Common side effects of these medicines include:

  • Constipation.
  • Dry mouth.
  • Headache.
  • Heartburn or indigestion.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Problems related to the dosing of dopamine precursors and agonists can occur, such as:

  • Rebound. This occurs when symptoms become worse at the end of a dosing period, usually late at night or in the morning.
  • Augmentation, which means that symptoms generally get worse. Symptoms begin to be noticed progressively earlier in the day, often in the afternoon or evening. Augmentation is most often a side effect of long-term dopamine use and usually becomes worse with increasing dosage. People with severe augmentation have symptoms constantly. The discomfort may intensify and spread to the torso or the arms. Stopping the medicine will usually return symptoms to the level that the person had before starting the medicine. At first, though, symptoms may temporarily get worse.

Dopamine agonists and levodopa may cause impulse-control disorders in some people. Impulse-control disorders include uncontrollable or problem gambling, sexual behavior, and shopping. Binge eating is another example.

People who have a higher risk for an impulse-control disorder:

  • Are young and unmarried.
  • Smoke cigarettes.
  • Have a family member who has a gambling problem.

Dopamine agonists are more likely than levodopa to cause impulse-control disorders. The risk is even higher in people who take both a dopamine agonist and levodopa. If you are concerned about taking these medicines because of this risk, talk with your doctor.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.



  1. Lesage S, Hening WA (2004). The restless legs syndrome and periodic limb movement disorder: A review of management. Seminars in Neurology, 24(3): 249–259.


ByHealthwise Staff
Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine
Specialist Medical ReviewerColin Chalk, MD, CM, FRCPC - Neurology
Last RevisedMarch 10, 2011

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