Levodopa, also known as L-DOPA and sold under many brand names, is a dopaminergic medication which is used in the treatment of Parkinson's disease and certain other conditions like dopamine-responsive dystonia and restless legs syndrome.

[3] The drug is usually used and formulated in combination with a peripherally selective aromatic L-amino acid decarboxylase (AAAD) inhibitor like carbidopa or benserazide.

[3] Side effects of levodopa include nausea, the wearing-off phenomenon, dopamine dysregulation syndrome, and levodopa-induced dyskinesia, among others.

Excessive peripheral dopamine signaling is undesirable as it causes many of the adverse side effects seen with sole levodopa administration.

To bypass these effects, it is standard clinical practice to coadminister (with levodopa) a peripheral DOPA decarboxylase inhibitor (DDCI) such as carbidopa (medicines containing carbidopa, either alone or in combination with levodopa, are branded as Lodosyn[6] (Aton Pharma)[7] Sinemet (Merck Sharp & Dohme Limited), Pharmacopa (Jazz Pharmaceuticals), Atamet (UCB), Syndopa and Stalevo (Orion Corporation) or with a benserazide (combination medicines are branded Madopar or Prolopa), to prevent the peripheral synthesis of dopamine from levodopa).

[8] Inbrija (previously known as CVT-301) is an inhaled powder formulation of levodopa indicated for the intermittent treatment of "off episodes" in patients with Parkinson's disease currently taking carbidopa/levodopa.

In addition, levodopa, co-administered with a peripheral DDCI, is efficacious for the short-term treatment of restless leg syndrome.

The long term use of levodopa increases oxidative stress through monoamine oxidase led enzymatic degradation of synthesized dopamine causing neuronal damage and cytotoxicity.

The oxidative stress is caused by the formation of reactive oxygen species (H2O2) during the monoamine oxidase led metabolism of dopamine.

The increased oxidation can potentially cause mutations in DNA due to the formation of 8-oxoguanine, which is capable of pairing with adenosine during mitosis.

[22] This treatment was later extended to manganese poisoning and later Parkinsonism by George Cotzias and his coworkers,[23] who used greatly increased oral doses, for which they won the 1969 Lasker Prize.

[3] The neurologist Oliver Sacks describes this treatment in human patients with encephalitis lethargica in his 1973 book Awakenings, upon which the 1990 movie of the same name is based.

[33][34] Levodopa has been found to increase the willingness to exert effort for rewards in humans and hence appears to show pro-motivational effects.