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How long does it take carbidopa levodopa to work?

Medically reviewed by Sally Chao, MD. Last updated on Sep 21, 2023.

Official answer


The short-acting (immediate-release) formulation of carbidopa/levodopa takes effect within about 20 to 50 minutes. The long-acting (extended-release) formulation starts to work closer to the 50-minute timeframe.

When switching away from a short-acting formulation, the first dose of a long-acting formulation may take 1 hour longer than the immediate-release to take effect.

The combination of carbidopa and levodopa can also be delivered directly to the stomach via a tube. This method typically involves an initial dose given over 10 to 30 minutes, followed by a continuous dose over 16 hours. The effect is strongest after 2.5 hours of the 16-hour infusion.

Eating lots of protein or acidic foods may delay the onset of these medications when consumed close together. You may need to take carbidopa/levodopa 1 to 2 hours before a meal and plan mealtimes to avoid overlap between doses and eating.

The duration of effect is longer for the extended-release formulation of carbidopa/levodopa than for the immediate-release formulation. The effects of extended-release carbidopa/levodopa should last between 4 to 6 hours. The effects of immediate-release carbidopa/levodopa last for approximately 2 to 3 hours less time — about 2 to 3 hours in total.

  1. Mao Z, Hsu A, Gupta S, Modi NB. Population pharmacodynamics of IPX066: an oral extended-release capsule formulation of carbidopa-levodopa, and immediate-release carbidopa-levodopa in patients with advanced Parkinson's disease. J Clin Pharmacol. 2013;53(5):523-531.
  2. Hauser RA, Ellenbogen A, Khanna S, Gupta S, Modi NB. Onset and duration of effect of extended-release carbidopa-levodopa in advanced Parkinson's disease. Neuropsychiatr Dis Treat. 2018;14:839-845. Published 2018 Mar 22.
  3. U.S. Food and Drug Administration (FDA). SINEMET CR (CARBIDOPA-LEVODOPA) SUSTAINED-RELEASE TABLETS. Available at: [Accessed September 24, 2021].
  4. U.S. Food and Drug Administration (FDA). DUOPA (carbidopa and levodopa) enteral suspension. Last reviewed January 2015. Available at: [Accessed September 24, 2021].
  5. U.S. National Library of Medicine MedlinePlus. Levodopa and Carbidopa. Last reviewed June 15, 2018. Available at: [Accessed September 24, 2021].

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