What is ON and OFF in Parkinsons?

“ON” is when a dose of treatment is working, “OFF” is when its effect wears off.

2 min

These terms are used to describe the effects of drug treatment (usually levodopa) on problems with the movement in Parkinson's disease.

When a dose of levodopa is taken, levels of dopamine in the brain rise rapidly, alleviating problems with mobility. This is the “ON” phase. However, as the body metabolises the drug, levels of dopamine begin to fall and the symptoms of Parkinson’s disease return. This is the “OFF” phase, and it typically occurs just before the next dose of levodopa is due.1,2

As the cells in the brain that normally produce dopamine progressively die in Parkinson’s disease, patients become increasingly reliant on levodopa to stabilise their symptoms.1 However, there are several ways in which the fluctuations in dopamine levels associated with taking levodopa can be managed.

The way in which the dose of levodopa is delivered can be altered to reduce the difference between the high and low levels of drug that arise following normal dosing. Adding other medications that prevent levodopa being broken down in the body can help to stabilise dopamine levels in the brain.3

1. Kalia LV et al. Parkinson’s disease. Lancet 2015;386:896–912.
2. Cenci MA. Presynaptic mechanisms of L-DOPA-induced dyskinesia: the findings, the debate, and the therapeutic implications. Front Neurol 2014;5: Article 242. Available at: [Accessed October 2023]
3. Cabreira V et al. Contemporary Options for the Management of Motor Complications in Parkinson’s Disease: Updated Clinical Review. Drugs 2019;79:593-608


Date of preparation: October 2023