Carbidopa/Levodopa Therapy for Restless Legs Syndrome

Reviewed by: HU Medical Review Board | Last reviewed: March 2023

Levodopa was the first drug formally studied to treat restless legs syndrome (RLS). Also called L-dopa, it was first discovered as a treatment for the symptoms of Parkinson’s disease more than 50 years ago and was then tried on RLS patients. It works fairly quickly to reduce RLS symptoms and improve sleep quality.1

Generally, levodopa is no longer prescribed by itself but mixed with carbidopa. That is because levodopa by itself can cause nausea and vomiting when used alone.1,2

Levodopa has fallen out of favor for long-term use of severe RLS due to some serious side effects. Now it is mostly prescribed for short-term or occasional use in people with RLS that comes and goes. Examples include people who cannot sit for long periods during travel or who have occasional and severe trouble sleeping at night.

Dopamine agonists and alpha-2-delta-calcium channel ligands are now more likely to be prescribed for daily use for severe RLS.1

How does carbidopa/levodopa work?

Levodopa is a chemical that the body uses to make dopamine. Dopamine is the neurotransmitter (brain chemical) responsible for producing smooth, purposeful movement. So, more levodopa in the brain relieves RLS severity and reduces periodic limb movement during sleep.1

Brands of carbidopa/levodopa

There are several different brands of carbidopa/levodopa, including:1

  • Sinemet® (carbidopa levodopa)
  • Sinemet® CR (carbidopa levodopa ER)
  • Parcopa® (carbidopa levodopa) orally disintegrating tablet
  • Stalevo® (carbidopa/levodopa/entacapone)
  • Rytary™ (carbidopa levodopa ER)
  • Duopa™ (carbidopa levodopa) enteral suspension

What are the possible side effects of carbidopa/levodopa?

Some of the most common side effects of carbidopa/levodopa therapy include:1

  • Nausea, vomiting
  • Dizziness
  • Daytime sleepiness

Long-term use of carbidopa/levodopa can cause a serious side effect known as augmentation.

These are not all the possible side effects of carbidopa/levodopa. Talk to your doctor about what to expect when taking carbidopa/levodopa. You also should call your doctor if you have any changes that concern you when taking carbidopa/levodopa.

What is augmentation?

Augmentation is a serious side effect common to carbidopa/levodopa. Augmentation is when RLS symptoms get worse instead of better, even though the person is taking higher doses of the medicine. The drugs may work for shorter periods of time, or the symptoms may begin earlier in the day or spread to the arms. These symptoms are often worse than the original symptoms before drug treatment.

About 80 percent of people who take carbidopa/levodopa experience augmentation within a few months of beginning the drug. Once augmentation occurs, other drugs must be used to control severe RLS.1,3

People taking these drugs should see their doctor every 6 to 12 months to be monitored for side effects, especially augmentation.1

Things to know about carbidopa/ levodopa

This drug is generally taken 1 to 2 hours before symptoms begin.3

Levodopa can also cause rebound. Rebound means there is an increase in symptoms in the morning. About 20 to 30 percent of people who take this drug have rebound.1

Before beginning treatment for RLS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter medicines, herbs, and supplements.

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