Ropinirole, sold under the brand name Requip among others, is a medication used to treat Parkinson's disease (PD) and restless legs syndrome (RLS). In PD the dose needs to be adjusted to the effect and treatment should not be suddenly stopped. It is taken by mouth. Common side effects include sleepiness, vomiting, and dizziness. Serious side effects may include pathological gambling, low blood pressure with standing and hallucinations. Use in pregnancy and breastfeeding is of unclear safety. It is a dopamine agonist and works by triggering dopamine D2 receptors. It was approved for medical use in the United States in 1997. It is available as a generic medication. In 2020, it was the 156th most commonly prescribed medication in the United States, with more than 3 million prescriptions. Ropinirole is prescribed for mainly Parkinson's disease, RLS and extrapyramidal symptoms. It can also reduce the side effects caused by selective serotonin reuptake inhibitors, including Parkinsonism syndrome as well as sexual dysfunction and erectile dysfunction caused by either SSRIs or antipsychotics. Ropinirole is available in various preparations, ranging from a 0.25 mg tablet to a 5 mg tablet. The primary reason is dose titration. Prolonged-release tablets are available in 2-8 mg doses. For Parkinson's disease, the maximum recommended dose is 24 mg per day, taken in three separate doses spread throughout the day for the immediate-release formulation. The maximum dose recommendations of ropinirole for subjects with end stage renal disease (ESRD) should be reduced by 25% compared with those recommended for subjects with normal renal function. A 25% dose reduction represents a more straightforward dosage regimen in terms of available tablet strength, compared with a 30% dose reduction. For RLS, the maximum recommended dose is 4 mg per day, taken 1 to 3 hours before bedtime. A 52-week open label study had a mean dosage of 1.90 mg, once daily 1 to 3 hours before bedtime.